75 cr 125 elsinore carb issues

ritchunt
Profile picture for user ritchunt
Posts
6
Joined
5/26/2020
Location
GB
ritchunt
Edited Date/Time 5/28/2020 3:34pm
Hi is anyone running a 32mm carb on a 75 125 elsinore. The motor has been rebuilt and has a jemco pipe and running a wossner piston, ive fitted a 32mm oko flatslide the bike goes really well jetting is spot on with nice plug colour but im getting really bad blow back out of the carb to the extent that the filter is that wet with fuel its choking the motor and won't start again once you stop, pull the filter of and it will start and run no problem.

I also have another bike with a standard pipe and piston and im having the same issues, i tried a old 32mm mikuni and that seems to be worse.

Has anyone had any sucess running a 32mm carb or know of anything that may solve my problems?

Thanks Ritchie
|
450exc115
Profile picture for user 450exc115
Posts
663
Joined
11/6/2014
Location
Hebron, CT US
450exc115 5/27/2020 9:56am
5/27/2020 9:56am
It's a piston port motor. Your going to get blow back until the piston closes the intake port. If it really bugs you go find a GEM or other aftermarket reed valve for that model.
ritchunt
Profile picture for user ritchunt
Posts
6
Joined
5/26/2020
Location
GB
ritchunt 5/27/2020 10:15am
5/27/2020 10:15am
Thanks for the reply, i know that you will get a bit blow back i was hoping there might of been a way to avoid it without going down the route of fitting a reed block and drilling the piston.

Hasletjoe
Profile picture for user Hasletjoe
Posts
436
Joined
7/29/2013
Location
Haslet, TX US
Hasletjoe 5/27/2020 6:39pm
5/27/2020 6:39pm
I have 76 motor in a 74 chassis and it runs a 32MM carb. Bike runs clean, is a rocket (Don't we all thing we have the fastest horse in the race?) and been solid for years. If you can get your jetting specs off the older carb, I can probably dig mine out. Guessing here, but I think it is about a 240 main, 45 Pilot. Memory is fuzzy on needle, needle jet and slide.

So the bike runs fine with either carb but just douses the filter with fuel?

My suspicion would be the RH crank seal leaking and feeding excess oil into the cylinder. Has it ever replaced?


ritchunt
Profile picture for user ritchunt
Posts
6
Joined
5/26/2020
Location
GB
ritchunt 5/27/2020 11:11pm
5/27/2020 11:11pm
Hi, yes both bikes run great like you say they are little rockets for old bikes, but after a race once you shut it off it wont restart untill you either remove the filter or it dries out.

Needle clip is in the middle and im running a 40 pilot and 130 main the plugs a nice colour so im happy with the jetting really

Both are fresh motors new everything. My friend rode one of them and was that impressed he built himself one..... and he is also having the same problems.


The Shop

See All »
ritchunt
Profile picture for user ritchunt
Posts
6
Joined
5/26/2020
Location
GB
ritchunt 5/27/2020 11:18pm
5/27/2020 11:18pm
What carb are you running? We where thinking it could be a issue with the carbs themselves but we tried a old round slide 32mm mikuni and it seemed to make things worse.

Thanks
MaxPower
Profile picture for user MaxPower
Posts
2646
Joined
8/15/2006
Location
NJ US
MaxPower 5/28/2020 3:34pm
5/28/2020 3:34pm
Just brainstorming, could timing be the slightest off causing some kind of backfire before the piston closes the intake port?
ritchunt
Profile picture for user ritchunt
Posts
6
Joined
5/26/2020
Location
GB
ritchunt 5/29/2020 7:45am
5/29/2020 7:45am
I will double check it this weekend. But I'm pretty confident its correct.

Post a reply to: 75 cr 125 elsinore carb issues