81 250r Knocking?

[Yenko502]

Whats up, i have an 81 250r and when i got it, she needed a new piston because it had a chunk of it missing from being ran with straight gas. Since then she has been rebuilt and bored to 71mm and has a forged weisco piston. Ive never heard another 250r running with a stock piston so i cant compare but i am experiencing a sort of knocking in my cylinder. not sure if its because forged pistons are naturally more noisy or if i have a problem that i need to look at. Any input would be appreciated. i am running a fuel mixture of 22:1 if that helps any.

Couldn't figure out how to attach a video so i put it on youtube: http://youtu.be/Xa_g4x4U41o

[BOB MARLIN]

Mine started knocking right before the crank bearing let loose.

[poolieZerUK]

Could be as above or shite from old piston in the crankcase or detonation you need to check carb and timing settings, any damage to cylinder head dome?

[shortline10]

A rod knock will sound louder under a load so did you ride it yet ? The air cooled motors are known for making that noise and with out hearing it in person it sounds normal to me .
Are all your cooling fins rubbers still present , they help to deaden that noise .



Whats up, i have an 81 250r and when i got it, she needed a new piston because it had a chunk of it missing from being ran with straight gas. Since then she has been rebuilt and bored to 71mm and has a forged weisco piston. Ive never heard another 250r running with a stock piston so i cant compare but i am experiencing a sort of knocking in my cylinder. not sure if its because forged pistons are naturally more noisy or if i have a problem that i need to look at. Any input would be appreciated. i am running a fuel mixture of 22:1 if that helps any.

Couldn't figure out how to attach a video so i put it on youtube: http://youtu.be/Xa_g4x4U41o

[El Camexican]

There is a post on here somewhere about this and I recall someone (maybe Mosh?) mentioned something about counterbalance bearings and noise on a 250R.

Did you rebuild the entire engine, or just the top end?

[Bren_downe]

Have you heard a air cooled R run before? They are known to be noisy. If your sure the top end is good I would do a leak down test.
This topic comes up every so often.

[fabiodriven]

Sounds perfectly normal. Don't be afraid to give er hell.

[atc300r]

Sounds normal to me.I have three aircooled 250r and my 81 has a NOS motor and it sounds the same.The 300 topend is noisyer than the 250.

[Yenko502]

Could be as above or shite from old piston in the crankcase or detonation you need to check carb and timing settings, any damage to cylinder head dome?

I took the whole engine apart to inspect it all for damage. There was no damage to anything other than the piston and cylinder walls, but that was taken care of. i reassembled it while being carefully guided by the owners manual.

[Yenko502]

A rod knock will sound louder under a load so did you ride it yet ? The air cooled motors are known for making that noise and with out hearing it in person it sounds normal to me .
Are all your cooling fins rubbers still present , they help to deaden that noise .

i have driven it and the noise does not increase. but i do not have the cooling fin rubbers on anymore. i am looking to buy new ones as the old ones were damaged/missing, hopefully its nothing to major.

[Yenko502]

Have you heard a air cooled R run before? They are known to be noisy. If your sure the top end is good I would do a leak down test.
This topic comes up every so often.

No i have never even seen another air cooled R in person. Everyone i know that has trikes has 4 strokes.. I went through the whole engine so it should be good to go other than this concern i was having. i will perform a leak down test as soon as i can. thanks

[Yenko502]

Sounds perfectly normal. Don't be afraid to give er hell.

I hope she is finally at 100%. My R is the only one ive ever seen so i have little experience with them, just had a concern. i just wana smoke up the trails.. haha

[Yenko502]

Sounds normal to me.I have three aircooled 250r and my 81 has a NOS motor and it sounds the same.The 300 topend is noisyer than the 250.

Thank you for the response. This takes some weight off of my shoulders. i want her ready to taunt kawi's.