Removed the reed block and found this....give opinions please

[gb250]

I recently took on an '85 YZ250 to breathe some life back into. After stripping the bike to the frame, powder coating and re-assembling with care I have got the bike running and functioning well. Except the bike is exhibiting signs of reed valve problems. Excessive kicking to start, excessive fuel seepage from around the exhaust pipe-head connection (there is a decent gasket in there and it fits pretty snug with all 3 springs intact) and the spark plug is soaked when I pull it out after running the bike for a few minutes. It rides ok, but is a bit boggy when you crack the throttle. Not crisp and sharp. I am not sure of the jetting and needle setting, as well as I am not sure the stock settings and jet sizes. Its a Mikuni carb, didn't take down the model but I can if anyone can use it for reference. The air filter is clean and oiled. I will be emptying the tank and using a new pre mix, there was a little old gas in there which I added to for testing, also will pick up a new plug. I pulled the reed block and have found what looks to be some kind of backyard mod that someone has done. There is no stock reed stops which I believe should be there if stock parts are intact, and there is a set of 4 opening reeds present. A plate with 4 holes, with a plate with 4 fingers cover each, on each top and bottom of the reed block. It appears as though someone hack-sawwed off the reed stops as well. Will this cause the excessive fuel and trouble starting I am experiencing? I have some new Boyesen reeds on order and will be putting those in this weekend.

Attached are front.

Please help!

 

[IndyMX]

Those look similar to my Boyesen Pro Series reeds. (Dual Stage)

They don't have stops either.

That certainly looks too clean to be a "backyard mod".

I'd suggest that you clean & check the carb. Paying close attention to the float level & float valve. It's probably time to replace it.

 

[ZOMBIE666]

Those look similar to my Boyesen Pro Series reeds. (Dual Stage)

Yup, got the same ones in my 98

 

[whenfoxforks-ruled]

Carbon fiber reeds you hack off the stops, they will break the reed. I do believe the fiberglass does not require this. Check what is left of the stops, to make sure the edge is chamfered slightly where it was cut, no burrs. Do not over tighten them little screws, it will make the reeds buckle and not close entirely. Find out if that is the stock carb. Replace the float valve, check the float height, rule out mechanical issues, particularly the rubber boots and jet it. Good luck!

 

[gb250]

Thanks guys!

 

[Pete Payne]

They are definetly Boyesen Dual stage power reeds, no reed stops required. I think you need to tweak the carb a little and also make sure the rings are in good shape.