Runs with choke
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@OllieDTR
15~16mm
The 21 is the setting for the 26mm round slide Mikuni fitted to early bikes…Have you fitted the 240 main? There’s no way you should need a bigger jet than 25. Needle 1 groove up from the bottom. Airscrew 1&1/4 turns out…
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If it ran perfectly with your mates genuine.25 Mikuni pilot in it, it’s possible that the one you bought is subpar.
Get a known good one from sportaxracing, they are perfect. Edit: I can absolutely vouch for them
…It needs the proper main jet as well …
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@SpookDog
Right so, the mates 25 pilot jet worked the same as my 25 pilot jet but you had to have the airbox closed off a fair bit for the revs not to hang,I’ve ordered 27.5 and 30 from sportx place so should be here today
I tested the bike with them Chinese jets I put the biggest one I had in which was 37.5 obviously it’s not that big in genuine mikuni size but that worked really well with the airbox opened up almost to the size of the snorkel,
I think the 30 pilot will sort it out, I was just thinking if my airscrew is 1.5 turns out and it revs perfect does it matter I’ve got a big pilot?
The way I think of it all bikes are different so they all won’t work on stock jetting? I’ve got 0 air leaks and few mods so can understand it running a bigger pilot?
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@OllieDTR I don't think it matters within reason what size jets you end up running as long as the actual running of the bike is good.
A lot of this kind of stuff is caused by the vagaries of mass production, it's pretty common even with competition bikes for two people to buy the same model off the showroom floor, then find out one runs better than the other when they go out riding.
In the 90s Performance Bikes magazine bought a 500 miles from new damaged repairable Kawasaki KR1-S to make into a road racing bike. It didn't run very well (they dyno'd it at 45bhp and a good one of those is more like 60) so they stripped the engine and found the KIPS valves had been fitted the wrong way round at the factory and some of the port timings were over 1mm out. IIRC they got it blueprinted (which just makes every dimension in the engine exactly what it should be) by Stan Stephens and without any actual tuning this resulted in almost the exact power output Kawasaki claimed when they tested it again. It ended up being faster than some of the "tuned" ones they raced it against!
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What does ‘have the air box closed off a fair bit’ mean? It works ok?…
Try to post a video, or get someone on the phone to hear the ‘revs hang’ just to see how much of an issue it is. Are you trying to fix a fault or balance your ‘tuning mods?…
Put things back to standard to fix faults. Then when they are fixed go ahead with tuning, or modding. Otherwise it’ll just exasperate the problem…
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The slight bit of up and down movement to the needle makes no difference to the carb. It’s not a problem. They’re all like it…
There should be one either side of the clip…
Where did you land with your throttle valve cutaway? Itll be stamped on it somewhere obscure. A wrong size slide could cause issues (in my experiences)…
Another thing, try oiling your throttle cable. It’s a PITA but worth the effort. My throttle used to take time to settle, or hang at 1000+ rpm. Basically had a mind of its own. Putting 3 in 1 through it made an unbelievable difference to the bike…
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I’ve sorted the bike now, I’ve got some videos,
Trouble with a bike that been “molested” so what I did with airbox was cut a sheet of thin metal and tiger sealed it onto the top of the cut airbox then marked out snorkel hole size cut that out and tiger sealed that on, so it’s got the correct amount of air now, and jetting wise it’s on 27.5 pilot and 210 main, (I’ll have to do some plug chops) but airscrew all the way in so putting a 30 in and that will be sorted, I’ve even took it for a ride and it goes very well no more hanging revs and can snap the throttle from idle to all the way open and no hesitation, jet seems big but that’s what it is it runs lovely.The only reason I asked about the washer below the needle as mine didn’t come with any but I’ve bought some 0.5mm thick rivet washers that fit lovely in there I just wanted to know the original thickness of the one on the bottom so I can match it with these as without washer on the bottom it puts the needle even further down
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@OllieDTR Cool that makes it a 3RM02
Same as mine…Have you actually tried it with a.25 & a 240 main jet? It really shouldn’t need a bigger pilot and airscrew all in. Something is wrong there bud…
Have you tried spraying cleaner through the air screws ‘airway’? Could very well be blocked if it’s having no affect. I’ve found a chewed up o-ring under my airscrew before
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Leak down test on the airscrew airway? Just take the airscrew out, block off the air hole inside the carbs inlet mouth and blow through the hole the airscrew goes in…
Sorry to keep on bud, it’s just I had pilot jet issues that caused my head gasket to blow every 7-8 hundred miles. It can have knock on affects. I can’t help thinking that you’re treating the symptoms, not the underlying problem.
But hey! Not my bike
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I’ll give it a go mate cheers, just sorting the wiring out at the moment, trying to wire in the polisport headlight but it’s not having none of it so might have to get someone in that does electrics for a living and look at it, want to get riding before summer goes so rather Chuck money at it and get it done asap than save a few £
