OzVMX Forum
Marque Remarks => Honda => Topic started by: YZ250H on June 10, 2013, 02:19:34 pm
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Help Please guys
Having trouble with my little CR.
Here's where I am at the moment
New Crank seals
New bore, piston and rings (not done by me)
GMC airbox with YZ85 filter
GMC pipe
Standard carb with standard jetting (clean)
New high voltage coil. Ignition timing checked statically and with a timing light.
Spark checked OK with spark tester
new plug
The bike starts Ok on the kicker (second or third kick). RUn "OK" and revs out well when not in gear.
Trouble comes when you try to ride away. It just dies in the arse completely. >:( >:(
I'm at my wits end with this beast. Any ideas guys ?
I'm thinking maybe needle and seat ? Ignition coils ??
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Try riding off with the choke on and see if this helps, if it does jetting may be to lean to start with. Peter.
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Didn't help Peter :-\. Tends to die even worse with the choke. Fuely type stuff running out around the exhaust flange.
Flooding for some reason ??? I just don't understand the total lack of power :-\
Has a new inlet manifold and new boot from airbox to carb. New clamps.
New kill switch - haven't checked that out yet :-\
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Sounds like blocked jets.
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Thanks John. I will pull the carby off and soak it and blow it out again.
At this stage I'm prepared to try anything.
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Soaking wont do anything Tony, you need to remove all the jets and blow through them to make sure there not blocked. While the jets are out write down the numbers and double check there the right ones. There a great little bike.
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Check rear air passage's that feed jets also.
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Will do John. Thanks for the tips guys.
Looking forward to riding this beast.
I have had it for nearly 2 years and it's never gone properly. When I bought a "runs well" bike of ebay it didn't even have spark. The wiring was earthed and the timing was out 180 degrees.
Now I have time to look at it.
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Blow out passages and jets
Rag from motor work stuck in pipe?
Correct piston?
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Tony get rid of it and get yourself a KX 125A ;) rotary disc and 6 speed Elsinore beater ;D
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Umm how much do you weigh Tony ;) sometimes a couple/few/shitload of later life kilos be squeezing the life song out of the little 125's :D
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Tony get rid of it and get yourself a KX 125A ;) rotary disc and 6 speed Elsinore beater ;D
I won't say I haven't thought about it Bill. I love those early tin tank KXs. For me it doesnt matter how fast the thing is 'cause Im never going to win on it. I could race my 465 in a pre 75 125 race and get my arse well and truly kicked ::)
Umm how much do you weigh Tony ;) sometimes a couple/few/shitload of later life kilos be squeezing the life song out of the little 125's :D
I'm only a little bloke ::) at a spritely 85 kegs Tim ;D ;D. She should be up to that you would have though. I have ridden DJ's 125 X and Vandy's MX125 and had a ball on both of them. Mainlines 125F was a hoot as well.
Blow out passages and jets
Rag from motor work stuck in pipe?
Correct piston?
Incorrect piston was something I had thought about too Bazza.
I will give the carby a super thorough going over, check the float level again and see what comes out of that.
Thanks for the help fellas. All the people on here have taught me a lot.
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Blowing jets out is a thing of the past $20 at Aldi you have a ultra sonic cleaner , 20 mins later they look like new with dirt out of drillings air will never reach. Use kero or degreaser find a little plastic tea strainer type holder for your jets.
Check the needle code, have you had it running before on that carby?
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The main is 125. The pilot is 60. Standard. I haven't ckecked the needle or the needle jet but will do.
Everyone looks to be focussed on the carby, so I will spend some time there too.
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It's loading up. Was a problem when new, even more so now everything in the carb is most probably worn. You need to run a 45 pilot (they are hard to get) but this will still not totally eliminate the problem, or throw the Keihin over your shoulder & fit a Mikuni. A standard jetted 30mm will solve all your problems or you can go bigger if your engine is modified.
K
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Interesting Big K. God knows how old the carb is. The slide deosnt show obvious signs of a lot of wear but ...
I accidently bought a new boot for theairbox to a Mikuni. I also have a gem reed valve manifold with reeds.
Maybe I should just bite the bullet and get the Mikuni.
Thoughts ??
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Needle and needle jet are critical in the little zingers ! and if not adjusted/jetted right(too rich) they get a real flatspot ,they also get worn and throw it all out ! new mikunis work too :)
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I had a similar problem with my CR125 last year, it would start & idle OK but wouldn't go well with my weight on it. When i checked the compression it was down around 8 PSI. Turns out one o the rings was jammed in the piston groove. Have you checked the compression?
Also about 2 years back my RM was running like a dog. This turned out to be a piece of rubber from the back of the airbox getting sucked into the carby inlet whenever I gave it a fistfull. Are you sure there's nothing restricting the airflow?
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I would use a Mikuni and the gem seeing you have it. If you are to run the Keihin get a 45 pilot if you can. You'll go nuts otherwise.
K
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Nothing stuck up the muffler?
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Nothing stuck up the muffler?
Checked for sausages and bananas. All clear ;D ;D ;D
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So it free revs but doesn't move when put in gear. Check that you fitted the chain Tentpeg ;D
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You have ridden one before haven't you? They have zero bottom end...
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So it free revs but doesn't move when put in gear. Check that you fitted the chain Tentpeg ;D
ROFL ;D
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Big K would you generally say to go with the mikuni even on slightly later CR's like a 125RZ
Brett
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Check the needle and i'm betting it has the wrong one in it. It happened to me once and for the life of me couldn't work out what I had done . I had got an M2 needle mixed up with an M1 while stuffing around and it had a richer profile. I couldn't tell until I lined them up side by side. The original CRM1 needle is fatter in diameter on the bottom to mid. Hope this is of some help.
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Big K would you generally say to go with the mikuni even on slightly later CR's like a 125RZ
Brett
Brett a 32 or 34 Mikuni is a better carb for the 74-77 CR125's but there is nothing wrong with the Keihin on the 125RZ and RA models, the RA carb is 2mm bigger than the RZ carb and a better choice.
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Piston in backwards?
The bike starts Ok on the kicker (second or third kick). RUn "OK" and revs out well when not in gear.
Trouble comes when you try to ride away. It just dies in the arse completely. >:( >:(
My KDX was like this when I first fired it up, in the end I found the main jet was way too big.
It had the correct number, I suspect it had been drilled out.
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Fuely type stuff running out around the exhaust flange.
If "fuely type stuff" is actually fuel, me thinks you're having float/needle seat issues.
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So it free revs but doesn't move when put in gear. Check that you fitted the chain Tentpeg ;D
Helpful input as always Teddles - thanks ::) ::) :)
I checked and the chain is in fact connected. Likewise the gear lever is set in such a position as to select gears freely. ;D
Methinks If I go for the new mikuni I can get most of these issues in one hit (probably cheaper by the time I but new needle and seat and hunt around for jets).
I will try this first. Will let you know how I go. Is the joint in Townsville the best or somewhere else ?
30mm or 32mm ??
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I Used Hatrick in Townsville last week for a 38mm Mikuni for the CZ - $132 plus some spare jets and a bit of super fast post.
Spoke directly with Tom who was happy to discuss a bunch of jetting options.
Got everything in 3 days.
Pete
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Thanks Pete. Sounds like the go.
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Yeah TD Hattrick is the place to go. 32mm
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Thanks JO. I think this will save me a lot of buggerising around.
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I have a carby or two to try different jets.
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Done LOTS of CR125M/M1's and have found a standard jetted 30mm Mikuni (TD Hatrick) to be a direct replacement for 28mm Keihin with no jetting other than maybe needle clip position, to work great on standard engines. Of course some inlet air boot mods are necessary for perfect fit. I usually a 16mm spacer on the cylinder with Suzuki inlet manifold & air boot. The spacer seems to give them more bottom end as well. Obviously if you use the gem reed you may not need to space things. You can also purchase a specific Mikuni inlet manifold to suit the CR's now as well. Tested lots of pipes as well and found that '76/'77 CR125 M2/M3 & Circle F work best. You can almost use the word torque & Elsinore in the same sentence with either. Send your email and I can shoot you some photo's.
Cheers,
K
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Wow. You blokes really do have a vast amount of knowledge.
I think I will go for the Gem reed set up since I have it here. There will be little or no heat insulation / vibration insulation from the barrel. Is that an issue. What gaskets to use ?
I might do a mock up and post some pictures. Am I adding additional complexity by putting the Gem reed setup on it? I'm pretty there are no performance mods to the barrel. On the first oversize (!)
Thanks for the offer of the carbs Brad. A lot of information here to digest.
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Try ATV Unlimited for a mikuni with a big packet of jets for a $100 odd
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These are the bits I have collected. Looks like now is the time to use them :-\
(http://i202.photobucket.com/albums/aa49/tbarsby/009-2_zps07150e99.jpg) (http://s202.photobucket.com/user/tbarsby/media/009-2_zps07150e99.jpg.html)
(http://i202.photobucket.com/albums/aa49/tbarsby/008-6_zps74bfa446.jpg) (http://s202.photobucket.com/user/tbarsby/media/008-6_zps74bfa446.jpg.html)
(http://i202.photobucket.com/albums/aa49/tbarsby/007-4_zps066d2265.jpg) (http://s202.photobucket.com/user/tbarsby/media/007-4_zps066d2265.jpg.html)
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Only trouble with those cr125 Gem reed valves is they are a bit restrictive and you may lose some outright horsepower in place of the better bottom end. None of the privateer race teams used then back in the day. DG, FMF etc..
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I put a 32mm mikuni from townsville on stock M1 and made the world of difference. I havent touched the jetting at all from what Tom sent. slip it in and rev the shit out of it. Happy days
Cheers Troy
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I put a 32mm mikuni from townsville on stock M1 and made the world of difference. I havent touched the jetting at all from what Tom sent. slip it in and rev the shit out of it. Happy days
Cheers Troy
Yes I'd go for a 32 also..
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UPDATE :
Stoked to announce that after owning this beast for three years it is finally running as it should.
The new Mikuni carb did the trick beautifully. I ended up leaving the gem reed valve off. Still doesn't have much pull off the line, but once you do get it off the line it flies 8).
Thanks everyone for your help.
For future reference I ended up on :
VM32 from TD Hatrick
Main #240
Pilot #45
Jet Holder #P8
Needle Jet #159
Needle 6F21
Slide 3.0 (standard fitment for that carb)
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Maybe the old carby jets were drilled and not what they appear?
A lot of us used Methanol in those days and other exotic combinations of Fuel to make 125's make more power
your old carby may still be worth keeping, find someone with needle drills and do the go no go test to see what they actualy are.?
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Yep, I've still got the old carb, an NOS manifold and NOS Carb Boot. Will put them in the CR125 box in caseI want to sell it one day :o
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another classic is the tank breather hose.. check a wasp hasn't built a home in there restricting fuel input
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For future reference I ended up on :
VM32 from TD Hatrick
Main #240
Pilot #45
Jet Holder #P8
Needle Jet #159
Needle 6F21
Slide 3.0 (standard fitment for that carb)
Lucky you didn't run it on the 125 main
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You've got me wondering now. I'm gonna pull that carb apart and see if that was a typo :o :o
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You've got me wondering now. I'm gonna pull that carb apart and see if that was a typo :o :o
Don't worry Tony, Keihen (original carb) & Mikuni jets are way different in the way they express the sizes & generally don't interchange with each other ;)
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It's going to bother me, so I have to look :o :o :o
Thanks for your help to smed. I've only ridden the bike for a bit around the 2 acres, but I'm sure I'm going to love this bike 8) 8)
She's off to Wyaralong on the 25th of May for her first outing (with me anyway)
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Don't worry Tony, Keihen (original carb) & Mikuni jets are way different in the way they express the sizes & generally don't interchange with each other ;)
Keihin 125 jet is a 210 Mikuni jet, 240 mikuni jet is 135 Keihin jet.
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Hi, i haven't read all the posts sorry, but looking at the heading & providing it's got good compression, i'd cut the pipe in a couple of places so as to visibly see right through it [then burn it out anyway], also strobe the ignition timing as the original system used to retard off a lot at the top end & [might] like a bit more advance!!. Did a lot of laps [race meetings] on one of those when new & were just bullet proof little motors back in the day--6 speed & all by memory & a sweet changing gearbox. Cheers.
ps, had a 250 elsinore at the time & 125 was my brothers but i kept steeling it off him for longer rough races as you could just keep it nailed till the end [when i was young & fit lol]--had a new YZ125A before--or after [can't remember now] god don't get me started--depressed again now!!
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Keihin 125 jet is a 210 Mikuni jet, 240 mikuni jet is 135 Keihin jet.
Is there a list somewhere of these jet size match up's Lozza, It would be very handy when switching carb brands to get a ballpark jet starting size :)
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hope this link helps http://huntertoolup.com.au/forum/viewtopic.php?f=10&t=82
if it is correct ?
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Glad to hear its sorted, if you are looking at pipes, I have tried a FMF, pro form but by far the best I have used if Geoff Morris's pipe. Keep an eye on the mikuni to barrel manifold as I destroyed an engine because of a perrished unit only 18 months old last year at the nationals.
Enjoy
Cheers Troy
I cant believe John Tate said in an earlier post that the honda was a great little bike after all the shit hes given me with mine ;D
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the biggest problem with them is the cdi box as for the pipe std 77 model pipe is the best
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fat ba----d! ;D
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I see looking back you say it's got a GMC pipe fitted so ignore my 'cut it open' idea--thinking it was the original. Have had various smaller motors [last one was a PE175] that had popped the crank seal out on the primary drive side, it ran but was all gaspy & lean but also smoke terribly so was an easy diagnoses but if a motor popped the mag side seal out [no smoke] it wouldn't be so obvious [apart from the running] & if not thinking along those lines then one can spend a hell of a lot of time chasing ones tale, Been there lots over the years but the good thing is that once solved then you never forget the unusual faults.
One that i didn't solve [cos i was thinking crank seals lol] was by memory a kawy tandem twin [think KR1S], mate called me in to come up with ideas [crank seals or disc valve timing--but no] he fixed it, pulled the cylinders off & someone had used KDX or Yamaha pistons with the cut away inlet which was 'ok' except it had the front cylinder piston was in back to front, hence the cut away was opening exhaust port big time at tdc. Things you never forget. Think it's why the first guy sold it & becomes the second guys problem, then the bike shops problem, & people wonder why repairs cost so much!!.
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ive seen a yam dt400 mono that a farmer had put the piston was in arse about, must have ran for awhile but had seize marks all over the piston but with the chain taking out the clutch adjuster etc it ended up at the wreckers. the things the untrained do!!
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fat ba----d! ;D
Hey - I've lost weight Rossco ::) ::)
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I see looking back you say it's got a GMC pipe fitted so ignore my 'cut it open' idea--thinking it was the original. Have had various smaller motors [last one was a PE175] that had popped the crank seal out on the primary drive side, it ran but was all gaspy & lean but also smoke terribly so was an easy diagnoses but if a motor popped the mag side seal out [no smoke] it wouldn't be so obvious [apart from the running] & if not thinking along those lines then one can spend a hell of a lot of time chasing ones tale, Been there lots over the years but the good thing is that once solved then you never forget the unusual faults.
One that i didn't solve [cos i was thinking crank seals lol] was by memory a kawy tandem twin [think KR1S], mate called me in to come up with ideas [crank seals or disc valve timing--but no] he fixed it, pulled the cylinders off & someone had used KDX or Yamaha pistons with the cut away inlet which was 'ok' except it had the front cylinder piston was in back to front, hence the cut away was opening exhaust port big time at tdc. Things you never forget. Think it's why the first guy sold it & becomes the second guys problem, then the bike shops problem, & people wonder why repairs cost so much!!.
Thanks OTH - Crank seals was my first port of call. They are new.
I will report back after her first race meeting on 25 May at Wyaralong
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It sounds like you'll have "fixed" your problem with the carb. It is a 125 Elsinore so you just have to hold the throttle wide open & use the clutch. The words torque & bottom end power don't really go in the same sentence with CR125M.
Cheers.
K
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Keihin 125 jet is a 210 Mikuni jet, 240 mikuni jet is 135 Keihin jet.
Is there a list somewhere of these jet size match up's Lozza, It would be very handy when switching carb brands to get a ballpark jet starting size :)
Yep, http://www.allensperformance.com/jetsizeconv.html
RH column is Keihin/Dellorto equivalent ie 200 mikuni = 123Keihin/Dellorto 210 mikuni =125 Keihin/Dellorto and 220 Mikuni= 128