Hi, ive just purchased a feb 2014 jotagass 300 from a rider whos owned it from new, great bike however it seems to have a metallic knock or pinging noise from the cylinder during mid to high range revs when bikes under load, such as climbing, no really noticeable when ticking over even when reved, just obvious when riding, has anyone got or had similar problems with there jotagas? Thanks in advance.

There is a head insert that cures it (slightly lower comp ratio - I read this on someone's blog

Ive read about this previously, was hoping the previous owner would have looked into it, apparently puttig a keihin carb on the bikes help aswell

http://www.retrotrials.com/the-jotagas-diary/the-best-modification-yet-to-my-2014-jotagas-300

Can well understand you feelings about your KXF 450. Lots of MX lads I know are totally fed up with the high cost and frequency of top end rebuilds on 4 strokes, engine oil costs are also a regular complaint.

Some are even quitting MX because of it.

Edited December 21, 201411 yr by dadof2

My mate who has a Jotagas had this issue and he had a new head insert sent to him which helped but didn't cure it. He ended up bending the float valve in the carb to raise the height about 3mm if memory serves me correct and this totally cured it and made the response better though the rev range...

I've been told that there are 3 head inserts that Steve supplies that are all gold. confusing the neck out of everyone.

I can't remember which gold one I have but it did the trick. The lowest compression gold head insert would be the correct one

Thanks everyone! Just ordered the low compression gold insert this morning, i believe the dellorto carb may need tweaking a bit also and that should help! Cheers

Try making the spark plug gap a little wider. Seems to help combustion.

Pinking can be caused from a Lean condition, Causing the engine to run too hot, Check for air leaks and Try using a higher octane fuel, Shell V power is good, And also maybe some octane booster as well, And the low compression insert should help as well, See how you go on.