Full power 125 import ypvs what carb?

[cjr]

Hi folks, I'm having great difficulty finding out what original carb I need. French import, fully working ypvs. 1985.

I've been advised VM24, then told VM 26. Recently found tzr MK1 carb, marked as VM 26, but has power jet pipe. Small black pipe between carb boby and bowl. Just want original carb name, reference, then jet etc sizes.

Grateful for your input. Not spending any more money until I get good, accurate advice, cheers!

[mellow]

mk3 2hk has the following.

MIKUNI VM26SS
ID MARK 1GU-00
MAIN JET 190
NEEDLE 406 CLIP POSITION 4
NEEDLE JET P-2
CUTAWAY 2.0
PILOT JET 25

MK 2 1GU IS SAME AS ABOVE FOR OTHER COUNTRIES.

For England it is the following:

MIKUNI VM24SS
ID MARK 12A-01
MAIN JET 195
NEEDLE 5GN36 CLIP POSITION 4
NEEDLE JET 0-2
CUTAWAY 1.5
PILOT JET 20

I would go for the VM26, It is what i run on my full power ypvs and yes i believe an early tzr 125 carb is the same, a 26mm.
Hope this helps.

[tony2stroke]

The correct carburettor will be 1GU-14101-10  which is a Mikuni vm26mm, the jetting will be as mellow said.


www.fowlersparts.co.uk/parts/4042917/rd125lc-1gu-1986-999-b/carburetor

[tony2stroke]

What size is the flatslide carb you had with the bike

[cjr]

Hi chaps, really appreciate the advice.

Flat slide has a central ID 28mm, air intake at rim ID 45mm. I assume VM 26 means internal ID 26? If so, no wonder why the bike smoked like buggary, and wouldn't rev past 8000. Plug was black, oily and visibly wet.

So with your advice going to buy the TZR VM 26. It's £80.00.

On another note, sprayed fairing and belly pan. Need to add decals and lacquer. Offered up fairing earlier, whole thing c**k-eyed. Bikes had a one front end dig, mainly affected near side. Brackets out, so will dismantle everything,Mildy bend until identical and try again.

Thanks again, Chris

[tony2stroke]

UHM! isn't the TZR carb a power jet carb, thought you already had a power jet carb, don't be too quick to spend money on it, the 28mm flatslide carb can be sorted to work well, its just not jetted right.

[cjr]

Hi Tony, sorry for the delay, been unwell.

I'm such a dimwit, lack of knowledge is I never realised the flat slide was a power jet carb, but it explains the 110 jet, which I think is too big. Just had a quick read-up and it says flat slide typically have smaller main jets, when I've been trying to put larger jets in to kind of meet to uk spec.

I'll take your advice and put the Polini flat side back on, down jet by .5 increments and see the outcome.

Cheers mate.

my stupidity brought this to mind; Shakespeare's response when asked the difference between ignorance and arrogance, ' I don't know and I don't care'....

[tony2stroke]

We all make mistakes mate, use some type of air filter though.

[cjr]

Hi Tony, Mellow, wanted to give you goods folks an update. Have fitted MK1 TZR carb. Bike's a buggar to start, but once warm starts and ticks-over, re-starts with a gentle kick and appears to run sweet. Taking it out today, feeling confident it may run better. Currently has 185 main jet.

As for X5, took out carbs when new 82.5 jets arrived yesterday and....It already has standard jetting. never mind, wouldn't have know otherwise. Got work bonus, bit the bullet and parted with £190 quid new front mudgaurd from Fowlers. Wanted a Givi screen, bought wrong size, large enough to keep the rain off half of Kent!

Cheers chaps..

[tony2stroke]

Apr 11, 2021 9:30:06 GMT 1 cjr said:

Hi Tony, Mellow, wanted to give you goods folks an update. Have fitted MK1 TZR carb. Bike's a buggar to start, but once warm starts and ticks-over, re-starts with a gentle kick and appears to run sweet. Taking it out today, feeling confident it may run better. Currently has 185 main jet.

As for X5, took out carbs when new 82.5 jets arrived yesterday and....It already has standard jetting. never mind, wouldn't have know otherwise. Got work bonus, bit the bullet and parted with £190 quid new front mudgaurd from Fowlers. Wanted a Givi screen, bought wrong size, large enough to keep the rain off half of Kent!

Cheers chaps..

TZR, Sounds like you need to give the carb a good clean, you really should look before ordering parts, otherwise you are going to end up spending on things you don't need, the more info you can supply the more chance we have in helping you.

GT, You have the manual and parts list no excuse now, read through it all and check everything.

It is not so easy remotely identifying running issues.

Here is a link to the Mikuni VM manual, again you need to read through it, this will help you understand what your doing.


www.mikuni.com/c-manuals.html

[tony2stroke]

I forgot to say, in the case of the TZR carb, as it is hard to start, but otherwise seams to run OK, I would suggest you check the tinny little jet for choke in the float bowl is clear, if that is blocked, then the choke won't work.

[cjr]

Thanks Tony, done what you said, carb off and another good clean choke definitely works, the affect on the tick-over is instant as it revs high. Whilst it was off, checked main jet and it's marked 180RD. I hoped the bike would work better, but it bogs at 7k rpm. if you gently tease throttle it revs a little higher and has a mini-burst of power, almost like its about to fly, but doesn't.

As for starting, realised it needs a couple of gentle kicks, no throttle and starts ok

Today ordered 190 MJ. What I can't work out is there's a teeny carb pipe on the RHS that is linked to the bowl - could see this with carb cleaner. This must allow air-intake to the bowl, but I don't see why an extra air intake would do. I know there's no point in guessing until I have a MK1 TZR carb diagram, which I continue to search for. ta, Chris

[tony2stroke]

180 is correct jet, RD is not Mikuni, but they are good jets, what condition is the air filter in ? if its 10+plus years old, could be knackered, here is a parts list for TZR MK1 on CMSL USA, but has a exploded view of the carb for you.


www.cmsnl.com/yamaha-tzr125-1987-2rh-france-272rh-351f1_model37414/partslist/0008.html#.YHSoHejYrIU

[cjr]

Thanks Tony, appreciate the link - super useful. RD air-filter's brand new. Haven't done 50 miles since fitted. RD revved like a bag of spanners, bogging at 5-7k so
somethings not right. I've got round style MK jets up to 150, judging purely on looking, the hole in the 'rd' jet is basically the same, I'd expect it to look bigger, but might be my defective eye balls. Mikuni jets arrived earlier this week. Got 180, 190, 200. And this morning, the expensive X5 mudgaurd arrived.

Will update again when Mikuni jet in, thanks again, Chris

[simon998]

Where are you ordering your jets from? I was struggling to find a good range of genuine ones. Have carb issues with my 125lc too ffs

[tony2stroke]

Genuine Mikuni are best and available from here, the RD jets in the post above are old replacements for Mikuni that were great. www.allensperformance.co.uk/shop/

[cjr]

Hi, finally identified the bogging issue - air-flow. My nephew used to mess around with DT's & TZR's years back. He removed air-box cover and taped it up, slowly removing small sections until the bike revved sweetly and pulled really well. First time I had it really singing and pulling properly. Next fault is at full throttle, the slide rises above the internal pin, jamming it fully open, which should be mechanically impossible.

Looked at the link you sent me and the slide is all wrong. Skirt too short and cut-out different shape. The TZR chap up north is looking to send me an original. Tony, I never doubted your knowledge, in that any carb can be adjusted properly will work well, I just never figured bikes could be so fussy about air-flow. Might take MJ down to 185 when correct slide and needle is fitted. Will go to Allen's for future jets. thanks, Chris

[tony2stroke]

Apr 16, 2021 18:12:22 GMT 1 cjr said:

Hi, finally identified the bogging issue - air-flow. My nephew used to mess around with DT's & TZR's years back. He removed air-box cover and taped it up, slowly removing small sections until the bike revved sweetly and pulled really well. First time I had it really singing and pulling properly. Next fault is at full throttle, the slide rises above the internal pin, jamming it fully open, which should be mechanically impossible.

Looked at the link you sent me and the slide is all wrong. Skirt too short and cut-out different shape. The TZR chap up north is looking to send me an original. Tony, I never doubted your knowledge, in that any carb can be adjusted properly will work well, I just never figured bikes could be so fussy about air-flow. Might take MJ down to 185 when correct slide and needle is fitted. Will go to Allen's for future jets. thanks, Chris

Its been a learning curve for you, now you have plenty of info, and you are starting to understand your bike, Great, never take anything for granted, specially when buying second hand parts, you need to know enough to keep it running, and fix anything that goes wrong when your out on your rides.

Glad you didn't give up on it.

[cjr]

Hi Tony, thought I'd give an update on the RD carb issues:

Bike since my ownership was running premix 30:01 (what the bloke told me). Last week I fitted a cable to carb and pump, bled it, cranked it until oil arrived. Fitted see-thru 2T pipe. Done away with premix. Air-box all original. Fitted ebay £21.00 VM26SS and bikes works much better than ever before. Currently has 185 MJ, but recommended 195 going in tomorrow. Already it pulls far earlier, stronger and revs brilliant, starts really easy. Red-lines easy but slight hesitation between 8-10K RPM, may be under jetting.

You were dead right not to waste money on carbs. That TZR carb seller has gone quiet. £100 quid down the swanny. Allspeed now properly sealed at flange connection, so no leaks. Got no need for a MK1/2 Pipe and a MK3 one. Hoping someone might need them.

Thanks for all your help. Lesson is go standard, get it running sweet and work / tune from there. BTW I'm beginning to think the new Allspeeds are substandard compared to original. Really tinny. Bike sounds like a dirt bike revving thru to power. Quite odd. I appreciate those who fully restore bikes to pristine condition; but not me really. just want a half-decent bike that goes like it should.

Cheers, Chris

[museumman]

Here's a little side note for anyone interested.

I took a 1GU VM26 off one of my RDs and fitted it to my TDR Belgarda that came with a molested 28 Dellorto. Me wanting to use the bike, with the Italian carb costing too much to repair at that point in time.
The TDR is still quite a bit quicker than the RD, certainly up to 70mph, using the same carb with no change to jetting. I've not ridden the TDR with bigger carb yet, but I would be reluctant to change the carb on the RD away from standard if it can work well on a more modern design.
I've also used the VM26 on 10W MK1s when carbs were too bad to rebuild. They ran identical to the VM24 from what I could tell. I don't know how a tuner would get on with a Dyno though. Obviously the YPVS bike has a wider power band and presumably optimized with the 26.