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Post by seang14 on Oct 9, 2017 22:37:50 GMT 1
Hi Guys, I intend fitting 350LC Barrels, Pistons & Head to my 250LC over the Winter! I already have a 350 Pump I sourced from Arrow Double Discs on front wheel And a 350 Back wheel! What do I need to change in the Carbs and will I notice big power increase when Changedover!! Any help much appreciated!! Cheers Sean G 🤔😈
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p4ddy
L plate rider.
Posts: 41 
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Post by p4ddy on Oct 13, 2017 20:12:49 GMT 1
I could tell you if I could find my manual? I'm sure the jetting for each will be online ? As for noticing the increase in power?? Hell yea lol. When I done mine with oversize pistons (I'm sure it was then a 375) it was way more fun. Don't get me wrong as a 250 it was great and very reliable.
Now when I changed it as long as I had standard bars on it would wheelie so dam easy. However with drops it wouldn't without some persuasion like when it was a 250. I never thrashed it to top end but the change in midrange was very noticeable. Looking back I should have tried some different sprocket sizes for a laugh.
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Post by aid22 on Oct 13, 2017 20:39:00 GMT 1
The carbs are different on a 350, in that they have different jets etc. Have a look in a Haynes manual, it has it all in there.
Regards, Aid.
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Post by earthman on Oct 13, 2017 20:59:42 GMT 1
I'm thinking that I may have to go down this route myself, there just seems to be more 250's for sale than 350's period. Are any of these parts almost impossible to find now though??
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Post by aid22 on Oct 14, 2017 13:37:15 GMT 1
Not impossible but all 350 stuff is very sought after and 250 stuff will go the same way if things go the same way. You can can have a 250 top end machined to a 350 if you really want a 350. Personally I always liked the 250 more than a 350 just depends on what you want from a 2stroke bike.
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Post by jon on Oct 28, 2017 9:32:08 GMT 1
The carbs are different on a 350, in that they have different jets etc. Have a look in a Haynes manual, it has it all in there. Regards, Aid. It's not just the jets that are different, it's the carb bodies themselves also. 250 carbs can be made to work quite well though. My brother in law's 350LC had 250 carbs fitted back in the day. Jon |
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Post by Tobyjugs on Oct 28, 2017 10:36:36 GMT 1
I was using 250 carbs on a modified power valve engine with 65 hp with a tiny amount of stutter. I replaced them with some 31k carbs and there was no difference once set up.
You just need to set the carbs up correctly with the right jets etc.
I just kept changing pilot jets and main jets to suit. I was using the 5K needle, later i put some made to measure pipes on and i found out i was also using a P2 345 needle jet (i think standard in a 250 carb). The bike was running lean even with 500 main jets. This was solved when i fitted a P0 345 needle jet (I think standard 350)
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Post by muttsnuts on Oct 28, 2017 22:17:23 GMT 1
you are correct, you must change the needle jet and needle as a minimum to the 350 spec (later 4L0-01 settings), you will also need to go up one size on the pilot jet (that's one size up on the 350LC spec pilot)
after that you will need to play with the main jet, the pilot maybe too big, if so, drop it, but some like the bigger jet, some bikes don't, odd but true
I intend having a play with some 250 carbs on my test 350 to see what is the best combination of needle jets, needles and pilots to see what works the best out of the "box" so to speak
I am mega busy at the moment, but if I get chance I will have a play for a few hours one night and let you know
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Post by kman on Jan 1, 2018 23:28:09 GMT 1
Muttsnuts.
That would be super handy if you could post your findings
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Post by muttsnuts on Jan 2, 2018 14:26:26 GMT 1
um, sorry, didn't get chance to play with it and the test bike has been stripped now ready for a new test engine to be fitted (not a 350LC engine) so won't be able to have a play, so will have to wait for a bike to come in that has this combo I am afraid
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