Engine knocking when off load

[ButterFu]

Hi, guys first i think i should say thanks for the troubleshooting some of you did for me without even knowing it. Second im not new to mechanics but this is my first 2-stroke rebuild. I bought a kinda junky blaster but after a about 1 1/2 months and some money its a pretty nice ride. I just rebuilt almost everything and had the jug bored to the next size up .040 over. The problem is Im hearing a knocking coming from around the jug area. The piston fit perfect. The fuel is mixed 32:1 with 91 octane. It doesn't knock while under load just when the clutch is depressed and it revs. I tried some jets and came up on 290. Im in the process of breaking it in got about 20-30 mins of runtime on it. let me know your ideas THANKS

ButterFu

 

[NOVIS]

mine did the same thing before i rebuilt it and after. im pretty sure its normal, ive never seen a blaster that didnt do it. i wouldnt worry about it, but i may be wrong.

 

[nd jat]

have you checked rod play and crank play when you had it apart? I had to replace crank cause the rod hammered out the bearings on the crank, which made a knocking noise.

 

[ButterFu]

I Checked it but i lack good precision measuring tools I have them but they are just not so easy to read. It wasn't bad but probably wasn't spot on. I was thinking that i could be the crank and rod. But its such a minor knock that if it is the rod/crank i won't worry until it gets noticeably worse (for monetary reasons this build has cost more than expected already). I am open to any more suggestions Thanks

 

[darederek]

i think that is a blaster thing. most make a little clinking type noise when idling. i don't know what kind of knock you are talking about

 

[xJust_Causex]

Mine sounds like a diesel at while running and it has done that seen we had it.