OzVMX Forum
Clubroom => Tech Talk => Topic started by: PE MAN on January 26, 2011, 05:48:31 pm
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was just wondering how a old 2 stroke will go with a modern day carb. carbys have come along way in 30 years when it come with cars. do 2 stroke act the same or would you have to get the ports matched to suit. or is that only if you intend to go bigger
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May not make any more absolute horsepower, but will without doubt start more easily, and run up through the rev range better. You can go bigger, but then you will have to port to suit. Depending on the bike in question, you may just enjoy the improvement by itself and leave it as is : the same, but BETTER !
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IMO Bings make the best HP.
There a cruel mistress needing much work to get perfect. Sometimes it just dosen't work out because you cant find beg steal or buy the right needles but when it dose thou the seamless perfect horsepower is worth it.
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More depends on the engine it's bolted to, a fully optimised engine responds to a better carb, a stocker won't know the difference. I saw a dyno graph of the same engine with 28mm PWK and a 28mm VM runs. VM made less at peak but was a mile ahead on the run up to peak power. The flatslides have better throttle response especialy the cresent shaped slides.
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GD66 you have answered that perfectly! I agree 100% that there is bugger all HP improvement with out other items matched to the carby, but things... may.... operate more friendly allowing you to concentrate on riding better = more speed and less strain. Cheers Tim754
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Gee. It's amazing that the factories ever sold any bikes considering how much needs to be done to them to get them to (apparently) run properly. ::)
They musta been just slappin' 'em together any old way.....
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Gee. It's amazing that the factories ever sold any bikes considering how much needs to be done to them to get them to (apparently) run properly. ::)
They musta been just slappin' 'em together any old way.....
The more money you spend on them the faster you go.
This principal is open ended.
Light speed has been a barrier but could be overcome with a little bit more money and flashy new riding gear of course.
Gav McLeod won the 250 class at one 4day on a bog standard XR200. He also rode a XL500 to Wiepa , stripped the road gear off and won his class. :o
I,ve owned a few bikes with BINGS fitted and never had a problem or complaint.
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the motor is stock pe400 besides a GMC pipe that will be here shortly... dont want to muck around with the cylinder just yet. when it comes time for a rebuild then might.
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Well, unless the stock carb has been caned mercilessly for a huge mileage by a ham-fisted ruffian, or it's gunked-up beyond redemption, it'll probably be ok to use with a thorough cleanup : maybe just jet it up a size or two depending on Geoff's suggestions with the use of his new pipe.
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I found that my pe400t went better with Geoff's pipe on stock carb setup I am going to get a pe400 motor hotted up soon for my project that will have a disc front end I am going to use a mikuni 38mm flatslide with powerjet on that. ;)
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mmm sounds good frosty... i got a spare motor in the shed as well. minus piston & flywheel. sometimes i imagine of making it some ridiculous monster an try an think exactly what it will go like... lol
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Yeah cool buy a couple of sprockets would be my advice for your stocker watch out though to big and the chain will rub the case if you go one tooth down on stock sprocket you'd be amased at the difference front wheel is alot quicker to jump up in the air. ;)
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I changed from a mikuni tm38 to a keihin pwk a/s on my bike as I wanted it to idle. it was straight forward to do but the problem is finding a jetting benchmark for older bikes I was lucky as it's a common mod for my bike so there was a ton of info available.
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yea had a 49 tooth on it before, went back to a 46 thought id like a little more speed.
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I go 48 rear try 13 or 14 front. ;)
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will do think there is just the stock standard 16 on there now
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I agree with Lozza,i remember my old PE175 being a good allround revver,nothing amazing about the way it went through the rev range.
After having to run the TM34 flatslide in my RM175 project because of the lack room,i find it very crisp in bottom to upper midrange from what i remembered my old PE being like.
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The PE experts back in the day ditched the standard round slide mikunis for Delortos.
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I am interested to try my 38mm mikuni flatslide I can then get it really tuned up with my mate that has a dyno and do some plug chops and change the jetting and with the power jet I should be able to get it good all the way though the ranges. ;)
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Once again, this forum amazes me with its members' denial of the last 30 years of technological development. Yes the old stuff works great if its adjusted correctly and not worn out - but the original question was about how an old motor would go with a newer carb and most of the time they will go better.
No doubt you all drive XE Falcons an VH Commodores because "they're just the same as the new ones"... ::)
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Once again, this forum amazes me with its members' denial of the last 30 years of technological development. Yes the old stuff works great if its adjusted correctly and not worn out - but the original question was about how an old motor would go with a newer carb and most of the time they will go better.
No doubt you all drive XE Falcons an VH Commodores because "they're just the same as the new ones"... ::)
I dont think its this forum in general Nathan ,just that some like a challenge and are keen to have a go..but in the end purchase that ellusive bit and still enjoy the game 8)
cheers A
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Once again, this forum amazes me with its members' denial of the last 30 years of technological development. Yes the old stuff works great if its adjusted correctly and not worn out - but the original question was about how an old motor would go with a newer carb and most of the time they will go better.
Most people would get more benefit from shelling out for riding lessons than playing 'murder in the dark' with their engines....
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PE Man, I just put a brand new 36mm Mikuni on my PE400 and before I lost my spark it ran great. good acceleration, easy to start etc. Only cost $220 delivered from the Aus Mikuni dealer in Townsville also. Couldn’t tell you if it ran any better as I don’t have the old carby.
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Gee. It's amazing that the factories ever sold any bikes considering how much needs to be done to them to get them to (apparently) run properly. ::)
Man you have never owned a Harley ;D
Anyway usually a flat slide well jetted will give you quite an improvement particularly if you started with a flogged out round slide with piss poor jetting. Jetting it right will make the difference of night and day to a 2 stroke regardlesss of carb.
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If I was building a new bike and was going to run NON BING I wouldn't even hesitate to buy a brand new Mikuni
For $200 bucks you get so much less hassle than trying to fix some old worn out stuff. Bings are a little different as there $600 plus for new ones.
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Once again, this forum amazes me with its members' denial of the last 30 years of technological development. Yes the old stuff works great if its adjusted correctly and not worn out - but the original question was about how an old motor would go with a newer carb and most of the time they will go better.
Most people would get more benefit from shelling out for riding lessons than playing 'murder in the dark' with their engines....
;D :)
No doubt the bike will probably make more hp with a new "modern" carb, BUT will you go faster?
When I was young I fell for the bullshit and changed the carb on my KTM. The motor went POP, so I changed it back and had no problems after that.
My point was that Gav WON on a bike that made 18? hp and he was racing guys on bikes making 48? hp. :o How did he do THAT?
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PE Man, I just put a brand new 36mm Mikuni on my PE400 and before I lost my spark it ran great. good acceleration, easy to start etc. Only cost $220 delivered from the Aus Mikuni dealer in Townsville also. Couldn’t tell you if it ran any better as I don’t have the old carby.
This is a classic example of why many of us shop overseas. I just bought a brand new 36mm Mikuni from Weekend Warrior for $150 landed. It's admirable to support local merchants but sometimes the much cheaper overseas prices make it a no brainer.
http://cgi.ebay.com/ebaymotors/36mm-Mikuni-Carb-AHRMA-Husky-Can-Am-Maico-Penton-CZ-/200569081741?pt=Motorcycles_Parts_Accessories&hash=item2eb2d94f8d (http://cgi.ebay.com/ebaymotors/36mm-Mikuni-Carb-AHRMA-Husky-Can-Am-Maico-Penton-CZ-/200569081741?pt=Motorcycles_Parts_Accessories&hash=item2eb2d94f8d)
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Once again, this forum amazes me with its members' denial of the last 30 years of technological development. Yes the old stuff works great if its adjusted correctly and not worn out - but the original question was about how an old motor would go with a newer carb and most of the time they will go better.
No doubt you all drive XE Falcons an VH Commodores because "they're just the same as the new ones"... ::)
A beige Volvo 240 actually ;D - a classic. Much more reliable and easy to work on than the moderns, and a tenth the price (http://i323.photobucket.com/albums/nn458/mx250syd/icons/smiley79.gif).
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After twenty years of trying to build old bikes on a budget, one thing that I've learned is that 90% of your initial tuning problems and set up time can be saved if you start with a brand spanking new carby. A few years ago I was given a brand new 38mm Bing type 54 that had been removed at birth from a Monty of some sort. Just fitting the new carb to my Maico without any jet changes at all cleaned up the running from top to bottom. I'm just about to purchase a new 36mm Bing from the mob below so that I can experiment from scratch with both Bing and the new Mikuni (see previous post) on my piston port 360 Yamaha. It'd take me a lifetime using cocked up second hand stuff, even if they show minimal wear. I'd love to try a late flat slide on the early engine but I presume it'd take a lot of setting up for nothing as I couldn't legally use it anyway.
http://www.bingcarburetor.com/offroad/offroad.html (http://www.bingcarburetor.com/offroad/offroad.html)
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It may have been covered in this thread or some where else but what is the ruling on later model carbs or the GCR's for racing purposes are you allowed to fit a carb that was not available back in the day?
#8
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;D :)
No doubt the bike will probably make more hp with a new "modern" carb, BUT will you go faster?
When I was young I fell for the bullshit and changed the carb on my KTM. The motor went POP, so I changed it back and had no problems after that.
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Yes you probably will go faster with more and smoother power, which is why modern carbs are not allowed in most VMX racing. Modern carb like FCR jetted correctly will perform like night and day compared to older factory carbs.
As for the carb making your engine go pop, no substitute for jetting it right.
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As for the carb making your engine go pop, no substitute for jetting it right.
No argument there. :)
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I remember my own 89 KTM350 ran like shit when I got it, the difference between very clean jetting and piss poor bottom end was one needle clip position. since then I have been prepared to spend the time to jet them right.
Some carbs also are more jetting sensitive than others so that helps to confuse the issue. Small changes on the Dellorto PHB seem to make a hell of a difference.
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For what its worth, i would go the way Frosty is going and fit a 38mm flatslide to the PE400 or maybe a 36mm if you want a bit more fuel enconomy. If flat slides were no improvement over the roundslides then they wouldnt make them. Yeah i know 99% of people would benefit from a riding school or newer suspension but wheres the fun in that. Bog standard bike rebuilds are boring, half the fun is in making your bike look personalized and enjoying shopping around for different parts you can add or change. What ever carby you choose, just make sure you pick a oil ratio (preferably what the bike manufacturer says) pick an oil, pick a fuel (preferably a high octane one) and then spend the time to get the jetting right to suit that and then dont change anything except if you maybe riding at different altitudes or to suit different temperatures or the type of course eg fast open or tight twisty.
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Comparing an old worn carb against a new carb (even of identical size) is like night and day. I've done a couple of swaps in recent years on TM's and RM's and as others have stated, there doesn't seem to be any more outright HP but the throttle response throughout the entire rev range improved out of sight :)
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I'm all for replacing old worn out carbs for new (of the same type). Saves a ton of head-aches.
I just feel people are giving themselves (and more-so the next owner after they've given up in disgust) a huge head-ache by trying to retro fit stuff in the vain (very) hope that they're gunna go faster.
Sure bikes have evolved in the last thirty years. Those titanium valves outa late model YZF's must be the ducks nuts! Why not try cable tying a coupla them to your swingarm and see if any gains are made there..... ::)
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I just feel people are giving themselves (and more-so the next owner after they've given up in disgust) a huge head-ache by trying to retro fit stuff in the vain (very) hope that they're gunna go faster.
Whether I ride fast or not I like to improve and mess with my bikes. Its only a headache if you don't know what you are doing and I don't give a shit about the next owner.
I like to replace heaps of stuff for reasons other than going faster, racing has been always about modification and having cool stuff. Look at MX even today, as good as the bikes are there are still a lot of modifications and the fast guys rarely ride stock bikes.
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Its only a headache if you don't know what you are doing
We'll leave it there then shall we?
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do you think my old man will notice if i take off a delotoro from his duke leight ;) think once there is some more cash in the bank might either try the 38mm mikuni like frosty or go with a 36mm bing.
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It may have been covered in this thread or some where else but what is the ruling on later model carbs or the GCR's for racing purposes are you allowed to fit a carb that was not available back in the day?
#8
FOR Classic and DT --If you have this years MA/MOM/GCRs have a read of 18.6.0.4--------- KIS
cheers A
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It may have been covered in this thread or some where else but what is the ruling on later model carbs or the GCR's for racing purposes are you allowed to fit a carb that was not available back in the day?
#8
FOR Classic and DT --If you have this years MA/MOM/GCRs have a read of 18.6.0.4--------- KIS
cheers A
Took a look ,thanks was I being a bit lazy really,
#8
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If you buy a new VM mikuni round slide, do you run it with the jets supplied as a starting point? Or do you have to buy the same needle, needle jet, main, pilot etc as was in your model. What I am asking does the carby work off the shelf with some fine tuning or do you have to make it identical to one removed as the jetting is very different.
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You may be able to run it off the shelf as a starting point but it will be just that a starting point. I have found a lot of suppliers will set up the carby for you if you give them the specs from a workshop manual, that is assuming you are running a stock engine.
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I bought a 38mm Mikuni for the YZ 465 from that mob in Qld (sorry, can't remember the name off the top of my head) and they sent it jetted as per the Yamaha manual. Very happy with it I was. :)
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Mikuni? T D Hatrick and co QLD?? or is that for Holley carbies?
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I've used a few used carburetors before and as yet "I haven't had a problem",managed to get carburation as good as it gets ??? Swapped a 32 for a 36 used the needle from the 32 ,main from the 36 and went up to 60 from 45 on the pilot.
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Yes. TD Hatrick. That's them. I couldn't believe how cheap the thing was as well.