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TZR 125 help needed, I'm at my wits end.


paule230
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TZR 125 (1998) YPVS fitted

After I restored my TZR 125 I had trouble with the bike spluttering and not wanting to rev over 3k. I put this down to rust from the tank blocking the carb jet, so after numerous cleaning both with the tank and carb I seemed to have got it sorted and on its last run out pulled like a train from 7k in all gears. Now its gone back to spluttering again.

The bike starts either 1st or 2nd kick when cold and always 1st kick when warm, revs cleanly from tick over, but try to ride it and it coughs and splutters from about 3k rpm regardless of throttle position.

I stripped the carb again and it was clean, I have fitted a costly metal and glass inline filter which also only contained spotlessly clean petrol (Shell V-Power)so i am sure it cannot be dirt in the fuel.

The best way to describe it, is it's like the choke is on preventing it from reving under load, but I know it's not and if it was then bike wouldnt revs when stationary.

I'm really at a loss now and to make matters worse, I have been approached about having my bike may get featured in a mag, so I have to have it sorted for then as a good article could help raise awareness of these bikes and put the values up which will help us all.

Any suggestions cos I just dont know what to do now and its getting me down :banghead2: as everything else on the bike is perfect.

Thank you.

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Could be an awkward one

Buy a couple more spark plugs and try them first.

I had replaced the plug when I got the bike back on the road, so this one has only done about 50 miles.

The plug colour is a nice dark tan / light brown. If the plug has failed after only 50 miles, what could cause this?

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I had replaced the plug when I got the bike back on the road, so this one has only done about 50 miles.

The plug colour is a nice dark tan / light brown. If the plug has failed after only 50 miles, what could cause this?

Ignition coil, or maybe pulse coil. Maybe a connection at the cdi or mag but i'd be looking at the coil, the primary circuit earth especially.

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Thanks all, Others have also said it sounds like it could be the stator plate which apparently isn't un-common on these bikes.

I'll update you all once I get my one tested etc.

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Hello

It does suggest the stator as an option.....but these might be daft suggestions and apologies if you have already discussed this elsewhere but, what is the possibility of the main jet being too large a size. I had a similar problem with an RD and a Dell-orto carb again at around 3,000 revs which pointed me to the main jet rather than the pilot jet. I got mine sorted out.............eventually :rolleyes: .

It would rev cleanly when static but kept bogging down under load. Another possibility could be the exhaust, apologies if it is new or you have already decoked it during the restoration.

All the best

Mike

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Cheers for the advice Mike, the carb is bog standard, with all the correct standard jetting and settings etc. The exhaust is ok aswell. The fault was intermitten which original made me think of the carb, but that has been stripped cleaned and adjusted many times :( , I also have a very good glass and metal fuel filter which shows just pure clean Shell V-Power.

Thats when I thought it must be electrical and others have now stated the stator plate could be the cause. I am waiting for West Contry Windings to get back to me with a repair cost, otherwise it'll be a new one.

The bike has only done 7k miles with one mature owner, well apart from me now. When the bike ran ok, it really flew as it has a fully working ypvs, rev'd right up to the red line on the road and I had been clocked at 97mph, pulled strongly and I'm 14stone!!!!

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Cheers for the advice Mike, the carb is bog standard, with all the correct standard jetting and settings etc. The exhaust is ok aswell. The fault was intermitten which original made me think of the carb, but that has been stripped cleaned and adjusted many times :( , I also have a very good glass and metal fuel filter which shows just pure clean Shell V-Power.

Thats when I thought it must be electrical and others have now stated the stator plate could be the cause. I am waiting for West Contry Windings to get back to me with a repair cost, otherwise it'll be a new one.

The bike has only done 7k miles with one mature owner, well apart from me now. When the bike ran ok, it really flew as it has a fully working ypvs, rev'd right up to the red line on the road and I had been clocked at 97mph, pulled strongly and I'm 14stone!!!!

Did you not just test it?

hey ho, yep them early ones really do fly when de restricted, you have upped the main jet when you fitted the pv?, it really needs a 240 in there or your 7000 mile motor won't last long.

Its the performance of these motors that makes me think the newer pv equipped bikes were neuterd somehow. I have very good memories of having the loan of an RDZ125 for a week and that just had the garage tune (both washers done, 240 main and the valve flipped) i just didn't tire of the bang at 7500rpm,

buuuuuuurrrrrrrrrrrr '7500rpm' poweeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeerrrrrrrrrrrrrr :D

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I havent sent the plate to them, just e-mailed them to get a estimate as I can get anew old stock one for £90.

The jetting for the restricted and full power bikes are the same according to the Yamaha work shop manual. Only the Swiss model according to it are different.

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I havent sent the plate to them, just e-mailed them to get a estimate as I can get anew old stock one for £90.

The jetting for the restricted and full power bikes are the same according to the Yamaha work shop manual. Only the Swiss model according to it are different.

Fair enough i'm not going to argue with the manual, what does it quote out of interest.

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This is as worded in the genuine (not Haynes manual) workshop manual for a 1987 2RK model TZR 125...

Main jet 180 (170 swiss)

Pilot jet 22.5 (20 swiss)

Jet needle 406-4

Pilot air screw 1-3/4 turns outs

Float height 20-21mm

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i had a similar problem when building my bike ......would rev fine when stood still but put any load on it and it would bog and eventually die....

turned out to be an air leek carbside ..... :(

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Air filter is new and def' not over oiled, you just get a slight smear of oil when you rub a finger over it.

I cant see it being a air leak as the plug is a perfect colour (wouldnt it be pale in colour if running weak?)and we have checked all the rubbers.

Once I get a quote from west country windings I'll decide what to do. In the mean time I'll get hold of a ohm meter.

The bike doesnt really bog down, its more jerky like its cutting out or hitting a limiter.

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  • 10 years later...

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