KTM ATV HQ Forums banner

1 - 14 of 14 Posts

·
Registered
Joined
·
207 Posts
Discussion Starter · #1 ·
Hi, just done with my renovation of my 450. But when I started it up it was knocking as hell, just like a Diesel engine. The valves are just done with 0.1 mm clearense. Can't really figure it out what it could be. Don't think it could be the camchain, it would more be a rattle sound if so.

Thank, Olle!
 

·
Premium Member
Joined
·
630 Posts
Hi, just done with my renovation of my 450. But when I started it up it was knocking as hell, just like a Diesel engine. The valves are just done with 0.1 mm clearense. Can't really figure it out what it could be. Don't think it could be the camchain, it would more be a rattle sound if so.

Thank, Olle!
Olle are you sure the piston is facing forward? I installed a piston backwards once and it did the same...

Also did you set the squish?
 

·
Registered
Joined
·
207 Posts
Discussion Starter · #3 ·
Olle are you sure the piston is facing forward? I installed a piston backwards once and it did the same...

Also did you set the squish?
Yes, I'm pretty sure that I did mount i right.
No I didn't just used the original gaskets that came with the gasketset.
 

·
Premium Member
Joined
·
630 Posts
Yes we are :)
Olle either the piston is backwards and the valves are not clearing it as the relief groves for intake are bigger than exhaust on the top of the piston or your squish is too close...what thickness base gasket did you use?
 

·
Registered
Joined
·
207 Posts
Discussion Starter · #7 ·
Olle either the piston is backwards and the valves are not clearing it as the relief groves for intake are bigger than exhaust on the top of the piston or your squish is too close...what thickness base gasket did you use?
Okej, well I'm sure that i mounted it right. And if it would be wrong, then the valves sould have taken damaged and it woulden't be going specielly good? But I fell no diffrent.

The Gasket dosen't I know about, diden't se anything that indicated that they should be diffrent.
 

·
Premium Member
Joined
·
630 Posts
Okej, well I'm sure that i mounted it right. And if it would be wrong, then the valves sould have taken damaged and it woulden't be going specielly good? But I fell no diffrent.

The Gasket dosen't I know about, diden't se anything that indicated that they should be diffrent.
Olle I hope some of the guys here will help...if it is metallic knock then the valves are most likely hitting the piston...

The only time I have ever seen this is:
1.) Timing was out but the engine wouldn't run because timing was out but if you turned the engine with the starter the piston would hit the valves
2.) Piston was installed backwards and the large OD Intake Valves were hitting the top of the piston but it ran fine - stopped engine and turned piston around
3.) Installed too thin of a base gasket on engine and it ran fine but at 3000 rpm or greater the piston would hit the valves - installed thicker base gasket and no problems

I did not damage anything in the #2 and #3 scenarios just corrected the problem and the Quad is still running at 49-50 Hp today....
 

·
Registered
Joined
·
207 Posts
Discussion Starter · #9 ·
Olle I hope some of the guys here will help...if it is metallic knock then the valves are most likely hitting the piston...

The only time I have ever seen this is:
1.) Timing was out but the engine wouldn't run because timing was out but if you turned the engine with the starter the piston would hit the valves
2.) Piston was installed backwards and the large OD Intake Valves were hitting the top of the piston but it ran fine - stopped engine and turned piston around
3.) Installed too thin of a base gasket on engine and it ran fine but at 3000 rpm or greater the piston would hit the valves - installed thicker base gasket and no problems

I did not damage anything in the #2 and #3 scenarios just corrected the problem and the Quad is still running at 49-50 Hp today....
Okej, well I guess that I'll have to take of the head again.
Can I drive with it even if the piston is backwards? Or will it harm the engine?
 

·
Premium Member
Joined
·
630 Posts
Okej, well I guess that I'll have to take of the head again.
Can I drive with it even if the piston is backwards? Or will it harm the engine?
No, it will damage your engine...you will have to turn the piston around correctly most have an arrow on the top. This should point to the front of the engine. If no arrow is on the top, look at the relief grooves in the top of the piston..the Largest grooves on the piston should go to the back of the engine and the Smallest grooves ahould go to the front of the engine...Intake Valves are larger than the Exhaust valves so they need the largest relief grooves to clear the piston...
 

·
Registered
Joined
·
207 Posts
Discussion Starter · #11 ·
No, it will damage your engine...you will have to turn the piston around correctly most have an arrow on the top. This should point to the front of the engine. If no arrow is on the top, look at the relief grooves in the top of the piston..the Largest grooves on the piston should go to the back of the engine and the Smallest grooves ahould go to the front of the engine...Intake Valves are larger than the Exhaust valves so they need the largest relief grooves to clear the piston...
Okey, the thing is that I'm absolutlie shure that the arrow is pointed forward. So that can't be the problem.
 

·
Registered
Joined
·
1,252 Posts
Okey, the thing is that I'm absolutlie shure that the arrow is pointed forward. So that can't be the problem.

well when i got mine when it is cold if you start it up it knocked like a deiseil and basicly all the time when it idled..but i turned up my idling screw...so now when i start it up t doesnt knock like a deisel..
 

·
Registered
Joined
·
650 Posts
auto decompressor maybe . . at under 1300 rpm the auto decompressor engage and the engine knock like a diesel for sure
 
1 - 14 of 14 Posts
Top