Suzuki PE250B needle jet series

[brent j]

Carburator question.
On the Suzuki PE250B the needle jets is listed as a Q-0. I have a Q-2 and want to change back. What I don't know is what series of jet I need. The manual doesn't mention what series and I don't know who changed the jet or if they used the same series as the original

Any help appreciated

[Tomas]

Check Mikuni OZ. My guess is that your needle jet is 159 series
https://www.mikunioz.com/shop/mikuni-159-series-needle-jet/?v=6cc98ba2045f

[brent j]

Thanks for that Tomas

The Q-2 that is fitted is a 159, I think the original Q-0 was a 159 but I can't be sure

[Tomas]

Just check the overall length and compare with web site. 159 will only fit VM 30,32,34 and 36 according to Mikuni OZ web site.
Also you can google "mikuni needle jet chart" for sizes. Q-2 is only 0.01mm bigger than Q-0. Not sure if changing back to Q-0 will make a lot of difference.

[James P]

The Q-2 that is fitted is a 159, I think the original Q-0 was a 159 but I can't be sure

Brent,

I can't advise with any certainty, as my own PE250B hasn't got its original carb. However, if a 159-series needle jet fits and works (including the jet's air intake hole aligning correctly with the air passage in the carb), then it would seem to be the correct one. If it is close, but something doesn't quite align properly with the 159, you may need a 166.

As far as I have noticed over the years, the 159-series needle jet seems to be the type available in the largest range of sizes of all types of Mikuni needle jet - a LOT of carbs used it.

Tomas may be right about not noticing any difference between Q0 and Q2 - do you want to change because of poor/rich running, or just to obtain the 'correct' size? Are there any modifications to your air box or filter which may have caused a larger needle jet to be fitted previously? Is the rest of the jetting (particularly the needle) standard?

Regards,
James

[brent j]

The motor in the bike when I bought it had a heavily ported barrel.
The jetting had been changed from std

I fitted a standard cylinder and want to get the jetting back to std. It was running a 50 pilot and the Q-2 needle jet.

I've gone back to a 40 (std) pilot but it runs better with a 42.5.

I want to get it running better for now but I need to wait till June/July to sort the jetting properly when our humidity and temperature are a bit better