@oldman There won't be much difference at wide open throttle, but at part throttle, the air can seep around the round slide, causing the fueling to be ever so slightly lean. It's not going to cause any issues, but that's a draw back of the round slide.
@declan The dellorto round slide probably has a power jet.
@runes Sounds to me that the mixer screw is the problem, as the mixture is wrong. It's either rusted or been abused and consequently the engines fuel/air mixture is wrong. If the plug is getting wet, surely that's from over fueling and the engine running too rich? Which would cause the starting problem you are experiencing.
I would get a new mixer screw fitted before doing anything else, so that you can adjust the mixture correctly and hopefully that should solve your problem. Then that way you will know for-sure if the engine's mix is correct and eliminate that from your suspected fault list before throwing a ton of cash on it. What RPM does the bike idle at???
Well it's broken isn't it.
I will ask that this is a separate problem and as such should be placed within the appropriate section, rather than reeds.
There are suppose to mount the exhaust to the frame with a rubber dampener. I guess Yamaha would be the place to get another one.
I never ran that one to be honest anyway.
@Jens-Eskildsen Absolutely, unless you have a DTRE CDI where it closes the port at 10K RPM. But earth the green and black wire behind the clocks and BOOM! Full power. Easiest bike to derestrict. It's like the Japs knew
have bought a second hand normal dt inlet that im going to trim out.i have the original 4dl 32mm joiner and will try to join that to the original.i have ho idea of the needle size thats currently in it but she is fairly thin and pointy.ive went the opposite way to you and bought a u1 needle to try.the jet size is a 148.
@Louis-James I used the wr200 cables as was a direct swap and I plan to put all new on the wr anyway, It seemed to take far too much air in, maybe try again at some point I'll just have to order a handful of jets and have done with it
I managed to find a company that makes precision jets for mikuni carbs (KMT Products) haven't fitted the 250 yet (240 standard I think) but have now reset then tweaked my mix screw and idle slightly and it is running much better in the lower rev range, no bogging when dropping gears etc. Feels slightly 'held back' in the midrange though and the same at the top end of the revs, with a slight 'cough' at full throttle. Hopefully will have time to fit the 250 main and raise the needle slightly this weekend and see how that does. It also feels as though it's revving extremely high in 1st & 2nd (pinned pv) then taking longer for the revs to reach 6.5K (hit the power band) in 3rd and upwards. Bit of a strange one, definitely a fuelling issue I reckon though...
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