Runs with choke
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@OllieDTR Looks like a good website to me but TBH I've never bought a Mikuni pilot jet so I wouldn't know how to measure them to ensure they're genuine. I think there's a set of gauges you can buy which are just labelled bits of wire the correct diameter.
Mikuni main jets you can get from PJME so it might be worth calling them and asking about the pilots, also try Allens Performance in the UK or Mikunioz.com (things posted from Australia arrive surprisingly quickly).
https://mikunioz.com/?v=13b249c5dfa9
https://www.allensperformance.co.uk/
And I'd take a look at Yamaha France parts lookup, get the part numbers of the jets from a late model DTRe and then Google for these because someone somewhere might have a NOS one and if it's in a sealed bag with a Yamaha part number it's bound to be genuine.
Yamaha France is a very good resource generally; very accurate and they seem to have info for any Yamaha product, not just those sold in France and on a PC you can just hit Translate. As an experiment I keyed in the VIN number for my original 1990 white/red UK (i.e restricted to 12bhp via no YPVS servo and PV pinned closed) DTR I owned in 1992 and it showed the PV end cap on the barrel instead of the YPVS pulley, cables and servo. Obviously it made no reference to myself and several other teenage malcontents accidentaly on purpose reassembling these components by the side of the road to alter this about an hour after I bought the bike...
https://www.yamaha-motor.eu/fr/fr/service-maintenance/parts-catalogue/
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Thank you for all that info bud if doesn’t go un missed!
So today I’m going to look at my slide to see what number it has on it, just looking at the emulsion tube needle etc it’s definitely the higher jetting rather than the dtre 210, 17.5
As yesterday I tried the 20 pilot that came in the carb and had to have the airscrew right in so definitely needs upjet so I can have it 1 to 1.5 turns out so with the 17.5 the standard DTRE engine has that’ll be to low, maybe it’s because it’s got some “performance mods” on to the bike bike now I don’t know, I’ve ordered from that jets place now looks like one of the better sites and got good reviews, I’ve ordered 210 main, 220 main, and 240,
22.5 pilot, 25 pilot and 27.5 pilot just incase I need to go to 27.5 not sure why I would but always good to have incase,
I paid £8 before for them other jets that should ring alarm bells as I got like 20 jets for that price
and now I’m paying £5 a jetReady for the road soon
I did order a horn for the bike from AliExpress and it cost me 40p with free shipping and it arrived in 8 days
it works like a horn and can’t complain for 40p -
Yeah, if you're going to use aftermarket jets then DON'T JET TO STANDARD! Jet to suit!
It's fine to have knock off jets, provided your entire collection is knock off.
I just buy genuine jets and stick to genuine.
240 genuine may be 210 or 260 knock off. So to say "It's stock jetting" but using aftermarket jets would leave us scratching our heads as to why it isn't working. Potentially leading us to misadvise and cost more money in the long run.
I don't have Mikunis in any of my bikes, they are all Dellortos and Eurocarb seems to have me covered on that. Dellortos were also used on the Belgarda engines as well as the Aprilia RS 125s and many Italian bikes. Common scene in the Vespa/Lambretta world and therefore abundance of parts available.
Not sure why you're having trouble with Mikunis...
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He bought the bike with the wrong jets fitted, You can’t get a .25 Mikuni genuine pilot jet in the UK for love nor money
I got a .25 pilot from sportaxracing and i know the bikes been running sweet since. It’s unmarked but runs perfectly. I really couldn’t comment on the others…
Only way to tell a genuine Mikuni jet is that they have a tiny ‘square in another squares corner’ stamped into them…
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So jets arrived today put 25 pilot in and runs a lot better but still hangs for couple seconds before idles good again. Air screw all the way in so needs bigger, I’ve ordered 27.5 and 30 pilot
Strange how big it is but all bikes different I guess
Mod listBoyseen dual stage reeds with rev plate
Dep downpipe and end can -
@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
