OzVMX Forum
Marque Remarks => Spaniards (Bultaco, Ossa, Montesa etc) => Topic started by: jerry on January 01, 2011, 12:57:21 pm
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Im on to one before I commit can anyone give me some history. On them. I think they appeared just before the Japanese onslaught and were outdated overnight. Is that correct? Did Gary Flood race one with some success? Thanks Jerry
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They were a bit dated when they came out- mainly cos of weight. The Mk5 before it was fast & 1 of the 1st 125s to have little/no flywheel, but they were unreliable. Their claimed max power was at 10,500rpm & at that rpm rear piston skirts broke - probably when you missed a gear. So for Mk 6 they 'solved the problem' by putting large (for a 125) flywheels on it which made them feel slow.
But I'm lead to believe the problem was the bottom of the Mk5 inlet port was flat, & even tho bridged it caught the skirt at very hi rpm. They changed the inlet port design on the Mk6 to an unbridged one with 'dished' (concave) bottom but also took the extra precaution of adding considerable flywheel weight.
The Mk6 actually had much better porting as they also added an extra pair of transfers & they make decent power but cos of the flywheels they were considered rather slow & by then were also overweight for a 125 so they were not very competitive. The Mk7 used the same barrel as Mk6, but lost a lot of weight, had closer ratio g'box & I believe less flywheel weight than Mk6 (but more than Mk5) & were almost competitive, so they can be made to work. The Mk8, tho an entirely diff barrel, had similar inlet port to Mk6 &7, & none of the MK6,7 or 8 had the piston skirt probs of the Mk5 IIRC.
Gary Flood probably did race one, no doubt modified, but that seems to be about the time he ceased racing 125s.
A 250 top end bolts onto the 125 pursang bottom end & is a very competitive bike if you wanted to go in that dir'n..
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Your comments are much appreciated JC thanks for taking the time! I picked up on the 250 top end thing. Are you saying head, barrel, piston will work on the 125 lower end? What about gear ratio's are they the same for either bottom end? If that's true it makes the exercise much more appealing as I believe all the running frame, wheels, suspension are the same and then I just have to chase a 250 top end and put green plates on her! Jerry
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Hi Jerry,
I just had a look at my numbers book and found that from Mod 30 Sherpa-S till the Mk 6 Mod 100, 125's Pursangs all had the same gearbox ratio's, (and the 250's and 360's till Mk10) the Mk 7 Pursang 125 was where the ratio's changed for the 125.
There was no Mk 8 125 and the Mk 9+10 125 Pursang had a gear primary and a six speed box.
The torque/power of these engines was also varied as John says by using different ignition flywheel and primary drive weights.
The Mk 7 was the first with chromoly frame ,hence the weight difference over the Mk 6.
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Moto did I read your post correctly. The bottom end (ie same gearbox) is the same for 125, 250 and 325 for MK6? Cheers Jerry
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Very intesting ! Without doing the homework are the rod /bigend/ little end the same on all size's :-\ ? on MK 5/6 would you need to change rod or crank (or both) for each size 125/250/325 ? cheers
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Gday Jerry,
I certainly remember Gary racing a Mk6 125 and he was very fast on it, but in saying that he was fast on anything that he rode and also Bert had a way of making the slowest bikes very fast. I had a new mk7 125 and 250 in 74. Bert did my 125 motor the same as Gary's and he also put it on methanol the same as his but the thing that we couldn't buy for mine was his tallent. My understanding was that all the mk6 bottom ends were the same but i can't swear to that. I reckon you should grab it if it's reasonably priced Jerry. The mk6 may not be the most collectable model but their not making any more of them.
p.s "Moto", what did you mean when you said there was no Mk8 125? I certainly bow to your knowledge of all things Bultaco but I thought I bought one on the way to CD7 which you would have looked at up there.
Also "Moto" your crankshaft jig is being picked up from me today.
Regards Stan
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Gary Flood did ride a Mk7 125,that my Dad brought off Bert in 74 I raced it in Juniors and we had to Lend it back to Gary for the last round of the Vic championships so that he could win the series,the bike was as you would expect very quick and easy to ride,had a lot of extra's in the barrel like transfers and holes in the side and rear of the piston.had a GP alloy tank because it was on methanol,and the rear shocks moved forward,they use to use the original rear shocks that were in the "conventional"position but would cut the shock bodies to make the shock shorter for the new positioning,I had previously been on a Husky 125 so once I got on this my results improved significantly,
Another good story of the 125 is the Mk8 that Bert built for Vic Allan to ride in 75 when Gaston Rahier came out we still had the Mk7 and Bert wanted to borrow the alloy tank so that he could put it on methanol for the Mk8 from memory Vic beat Gaston in one moto at the Aust titles in Tassy on that bike,Stan mat know a bit more about this,
#8
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last year l sold a beautiful complete 125 mk 8. and l was very silly in selling, l bought the bike off a fellow in Boronia Melbourne.
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Hi Stan,
You are right ,I missed the Model 144 Mk 8,It was a late night sleepy post, I appologise for that. Is your Mk8 going to be ready for CD?
Thanks for the news on the jig.I will buy you those beers when I see you ! I hope you were kind to Matcho Mick.
Huskibul and Jerry,
The bottom ends are similiar for all Mk 6 sizes 125,175,200,250.The parts book shows the conrod kit 125 to 250 all using the same part no.They all use 60mm stroke,just different bore sizes.The little ends all use a 16mm diameter pin but with different lengths.The crankshafts wheels have different numbers which I think relates to the different drillings for balance on the different size engines.
People used to just drop the 250 cylinder/piston and head on the smaller engines in the old days and I don't think the balance factor caused too many problems as the bike had just doubled its power so there were smiles all round,who cares about a few extra vibes!!
The Mk5 125 and 250 parts book shows a mixture of crank parts used,It was a changeover model and a lot of the part numbers are from older models(use up old stock?)The Mk 5 250 can use the same con rod as the Mk 6.
The MK 5+6 325 also have the 60mm stroke,but the cases are bored out more at the base of the cylinder to allow for the 83mm bore.They also have a larger big/little end bearing.Not sure about the size of the crankshaft wheels.This capacity engine is a bit of a different animal again.
I guess to summarise you should be able to drop any 125 to 250 cylinder/head combo onto any Mk 5 or Mk 6 (not 325) possibly with a few extra vibes!!
Jerry,
The gearbox was the same for all the engine capacities in the Mk 6 Models. Only the countershaft/rear wheel sprocket size was different.
Cheers.
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Thanks for that info moto! saves a hell of a lot of legwork chasing it up and gives a lot food for thought ! cheers ;)and good luck jerry with the 125/250 if you decide to get it ! imo it was an great period for the iconic bike's :)
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I fitted what I think was a Metralla 250 top end to my dreaded 125 Lobito and it made a reasonable difference but it didn't turn the puss heap into a monster. It turned an inadequate little bike into an almost adequate one.
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Thanks Moto your the man! The Mk5 "250" is going to complement my MK3. Stay tuned for developments as they come to hand. PS Your spot on Huskibul it was a magic era to be sure! Cheers Jerry
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Firko,
I still hear the salesman at Frasers laughing.
He sold you a bike that was designed to be ridden by a 15 year old. Then you came back and bought more parts to try and get it to perform like one of the adult models that you were too tight to buy in the first place!
Forty odd years later you still haven't got over this fact and its still the bikes fault .The Lobito story is getting tiresome.
Let it Goooooooooooooooooooooooooooooooooooooo
Cheers.
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Moto is correct w his pursang info (except the Mk8 M144 oversight)
However some 125 bottom ends can't take the 250 top end without opening the spigot in the crancases, but I think its only the early 125s (Sherpa S's etc). The 250 spigot is 80dia, whereas some 125s are only 75dia. However I just checked my Mk6 M100 barrell & crankcases & its 80mm.
There are definitely diff holes in the 125, 175 & 250 cranks to balance diff piston weights, as I have checked before. Not much diff between 125 & 175 but a fair bit between 125 & 250, as you would expect.
Altho the 325 uses same 60mm stroke it uses slightly larger dia crank halves & 20mm little-end (vs 16 for 125 & 250) & larger bigend (22 or 24mm IIRC vs 18 for 125 & early 250). Despite that, Bert Flood used to sell a kit to convert 125s all the way to 325s (still using the 125 rod!!) but its a LOT of work & not very effective. There's an article on it in an early Trail & Track.
Tony, you may remember Neil Harnsworth racing a SherpaS w such a conversion at the Six Mile track in Rocky back in the day. The conversion was done by Greg Day in Gladstone (to Floods instructions) where I used to work in the school holidays.
The std Mk6 125 was also 'strangled' w a 27mm carb, whereas the earlier 125 Buls had 30mm. Popular Cycling (PC) ran an article on modifying the Mk6 125 & they got over 20hp on the dyno from 7500 to 10,00rpm, peaking at 22hp. Pretty impressive. The changes weren't all that radical either. My friend in Bris had his barrel ported to the same specs on his Mk7 (same barrel) & won the Qld 125 VMX title on it several yrs ago. I rode it & it was pretty quick - comparable to an Elsie & much sweeter handling. He had a pipe built to the PC spec, but found a stock Mk6 pipe better than the PC or Mk7 pipes.
One thing to remember if you go the 250 top end route. Even tho the M100 had 4 transfers, it was a diff layout to the 250s 4 transfers. The M100s transfers are only about 27mm wide at base gasket/crankcases whereas the Mk6-8 etc 250s are 48/50mm. (IIRC, Mk6-8 all used same M103 Mk6 250 barrell. Moto could probably check that in parts books.) However all is not lost. The M100 125 crankcases have the larger castings to take the wider transfer ports, so they can be opened up w a dremel or die grinder.
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Firko,
I still hear the salesman at Frasers laughing.
He sold you a bike that was designed to be ridden by a 15 year old. Then you came back and bought more parts to try and get it to perform like one of the adult models that you were too tight to buy in the first place!
Forty odd years later you still haven't got over this fact and its still the bikes fault .The Lobito story is getting tiresome.
Let it Goooooooooooooooooooooooooooooooooooooo
Cheers.
Moto..Why do you blokes take any Bultaco criticism like a knife to the heart? I've had that dickweed el Presidente slander me way outside the realms of good taste in the press, Anthony Suttor cancel his advertising and subscription at VMX because he concieved some sort of bias against Bultacos in the magazine and I've had all sorts of rudeness thrown at me by Bultaco fans because I dared to criticize one of your precious little gems, all the time failing to understand that I was originally having a piss take....that's all, a bit of fun. I've kept going with it because you blokes are so thin skinned that I now find it highly amusing to see your reactions. I can bet that every time the Lobito thing comes up I'll get yet another frothing at the mouth Bultacophile have a shot at me. Welcome to the end of the queue Moto ;D.
Now a few facts you may be interested in:
*I actually like Bultacos, I started out on a Sherpa S and still have a soft spot for them. I'd own a 360 Bandito, Mk 7 360 Pursang or a Gold Medal Frontera in a heartbeat.
*I've written two detailed historical pieces for VMX, a lengthy piece on the Astro model in issue #31 and an even longer article on the history of the Sherpa S in issue #34 that despite good feedback from the USA and even Spain didn't recieve one accolade from local Bultaco fans. Interestingly though, you all react in rabid indignation whenever a satirical piece I wrote over 15 years ago is mentioned. Funny that.
*If the Lobito was intended as a bike for 15 year olds as you contend, why was it registered for the road and why does the advertising show smiling young adults having delerious fun on their Lobitos. Someone should have told the company's marketing department that they'd got it all wrong.
My particular bike of choice happens to be Maico and I'd love 2 bob for every time some comedian raises the old 'Maico Breako' chant. Does it cause me go all defensive? Not in the least. I couldn't give a shit what others think of Maicos. Bultacos are nice bikes but not everyone's going to like them. That's the way of the world. You guys could do with lightening up a tad and appreciate the difference between piss take and genuine criticism.
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Back on the thread, & further to my last post, I have never seen a Mk5 M86 250 pursang barrel, but it may be diff to M103 barrel. I suspect it maybe like the Mk5 M107 Matador barrel which had the narrower transfers (& 's' shaped finger ports cut in the liner). If so, it should go straight on the M100 bottom end w/out need to open up the transfers in the cases(as would an M107 barrel), but the porting wouldn't be as good as M103 w 4 proper transfers, I wouldn't think.
However, there are a lot more M103 or frontera barrels around than M86 barrels. Actually, the Frontera barrels (M152) have more radical porting than the M103, but technically aren't legal for pre75, tho the 103 barrels can be brought up to 152 specs quite easily.
My friend mentioned above also has an M120 Mk7 250 w legal barrel (M103) mildly ported & Pomeroy pipe from Hugh's in US & it absolutely explodes out of corners like a scaled cat - just like I remember Gary Flood doing back in the day.
Anyway, enough of my rambling. Grab it, & happy pursang-ing! Properly set up, they're a real sweet race bike. Certainly one of my very favourites. Tho remember the Mk6 is still RH gearshift (but can be converted to LH).
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Yeah that's right JC, i have both mod 86 pursang and 107 matador barrel's and their identical :)
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Thanks Huskibul, I often wondered about that.
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Firko,
I thought you of all people would know a good PISS TAKE when you read one.
You have been handing them out to people for years .Its your turn !!
The Lobito dribble you still rave about and people that offended you fifteen years ago.Does anyone on here know or care? I don't think so. Let it gooooo
As for your its about Firko CV on Bultaco's. Does anyone care? I don't think so. Let it goooo.
A knife to the heart,Frothing at the mouth,rabid indignation ? The end of the queue to where? Is that the far queue?
Are you writing for Mills and Boon now.
How about you cut your so called piss taking, the instigator of it is the only one who seems to know it is a joke.Its meant to offend,and mine sure has judging by your response.Just treat people like you would like to be treated,no nonsense.
Find somewhere else to take your dump.If you like Bultacos so much, put a positive post up here every now and then.
That bit where you have banished me to the end of the queue Mark, how funny is that. Its gold. You really need to find a room full of mirrors.
Cheers.
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Amen!
It's amazing how people can hide their antagonizing here behind a 'piss-take' or a ;D.
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I just spent half an hour writing a reply to Motos critism of me but I've decided that it just ain't worth the angst so it'll stay in my computer. This Bultaco thing has gone on long enough. I've tried to put my case that I don't hate any bike, especially Bultaco but what's the point...peoples minds are well made up and my defence only prompts more tit for tat.
Think what you like guys. My first post still stands.
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Moto,
I remember a bloke called Mick who had a Sherpa and is was a clever bike it could swim in the lake at Greenie and for Firko saying he would like to own a Bandido I always knew he was a sick bastard also have you seen the little wolf on ebay?? just had the first grandson arrive...may have to start talking bul again.
Harro
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Hey Grandad Harro,
Good to see you back - if you find another Bandido let me know, Bul talk is always welcome...
By the way check out this site www.clubbultaco.com.au (http://www.clubbultaco.com.au)
Cheers,
Mark
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Hi Harro,
Glad to hear you made it back ok from your sailing adventure, although we might have to test you to see if you are still batting for the right team. You know, long lonely nights on the high seas, a small boat full of blokes, ;) ;)
I had a call from the past the other day.Anthony Owens rang and we talked about some of the nasty tricks you pulled on him years ago.I gave him your address,he is still as mad as ever and said he had something for you, whatever that means.
Congratulations on being a Grandad,you know you wan't that Lobito to start his riding career off on the wrong right foot just like you did? :D or was it a Honda 100?
Cheers.
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Moto,
Anthony Owens.....jesus remember the coal track from Belmont Nth through to John Darling pit he used to clear those bridges on a Honda 90 scrambler man could he ride a bike and his brother as well Johnny a Bultaco boy.
The sailing was unreal went with another Belmont boy Tony Mowbray sailed from Cape Horn up through Chile and Patagonia to Puerto Mont and then Tony sailed the boat to Easter Island and then Tahiti I couldnt go as I only took 4 months off work and had to go home.
There is a smick Matador on evilbay looks tempting and hows the old girl going as I was going through some old photos of the Bul rally at Braidwood when I caught up with you after 30 odd years and the Montadero looked good.
If ever I win lotto TC I will shout us a ride through Chile Patagonia on a couple of 1200 GS you have to see this place its amazing start at Ushuia down the bottom and work your way up end up in Alaska....or maybe a Frontera for the adventure
Harro
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Auscobul,
Mark are you another bloke with a death wish wanting a Bandido good to see the Bultaco site up and running and there are a few good buls for sale at the moment six day Matador,Lobito little wolf and some real goodies in America Montadero,Bandido makes you dribble.
Hope all is well
Harro
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Picking her up tomorrow
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Picking her up tomorrow
Good one Jerry, I will look forward to seeing some pic's.
Stan.
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See what I can do Stanley. Was that Kawasaki contact helpful for you? Jerry
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See what I can do Stanley. Was that Kawasaki contact helpful for you? Jerry
Yes Jerry, thanks very much.
Stan.
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Have a feeling my MK6 has a MK7 frame. MK7 is chome moly how can I tell? Any help appreciated. Cheers Jerry
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MK7 is chome moly how can I tell?
Jerry, Jerry, Jerry
The best way is to drive over it with a truck
If it flattens completly then it is just mild steel
If it only half flattens then it is Cro-Mo
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Have a feeling my MK6 has a MK7 frame. MK7 is chome moly how can I tell? Any help appreciated. Cheers Jerry
What is the frame number Jerry?
Regards Stan.
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Hi Stan VB10001410 (matching engine # by the way) I have looked up the # and it tells me it's a MK6 but it has a tab welded on the rear stay (exhaust side) that I've only seen on a MK7 as well as a little loop thing welded near the swing arm pivot on the other side. It looks like an anchor point for a ?return spring for the rear brake. Also the the swingarm lower shock mounts have been beefed up considerably and maybe moved forward ?approx 1cm. The mods look professionally done.Maybe by the Floods ???? Cheers Jerry PS As for you Geoff get yourself ready for another visit to discuss a pipe for this project. Im thinking Titanium if your up for it!