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XLsior · 01-19-2024, 09:41 PM

After multiple plug reads, jet and needle changes trying to dial in the BOAO big bore kit and always hitting this threshold where peak rpm above 7000rpm hits a wall.

Trying to figure out if its a fueling issue with main jets and needle position the parameters between changes are so minor that I expect there should be enough crossover to the point 7000rpm WOT limit should be easy enough to cross...

Swapping CDIs pretty much confirmed to me its not an ignition problem...

So what exactly changed since the stock cylinder/headgasket failure to the bigbore/used engine valve train and cam...

Well by all merits the last possible culprit is the used valve assembly, specifically the valve springs...Going by the donor engine condition its quite probable the parts were tired and well used/abused.

So it is quite possible my issue has been valve float this whole time...

Ive done the jetting and needle position to death and the bike runs fine under 7000rpm below WOT..plug read is good.

If the valve springs are weak and can't handle high rpm then it seems like a viable explanation to my performance issues and woes...

In other words I think the head will have to come off for the umpteenth time.

01-19-2024, 09:41 PM	#507
XLsior Join Date: Aug 2020 Location: Australia Posts: 1,298	Doubling Back on full circle After multiple plug reads, jet and needle changes trying to dial in the BOAO big bore kit and always hitting this threshold where peak rpm above 7000rpm hits a wall. Trying to figure out if its a fueling issue with main jets and needle position the parameters between changes are so minor that I expect there should be enough crossover to the point 7000rpm WOT limit should be easy enough to cross... Swapping CDIs pretty much confirmed to me its not an ignition problem... So what exactly changed since the stock cylinder/headgasket failure to the bigbore/used engine valve train and cam... Well by all merits the last possible culprit is the used valve assembly, specifically the valve springs...Going by the donor engine condition its quite probable the parts were tired and well used/abused. So it is quite possible my issue has been valve float this whole time... Ive done the jetting and needle position to death and the bike runs fine under 7000rpm below WOT..plug read is good. If the valve springs are weak and can't handle high rpm then it seems like a viable explanation to my performance issues and woes... In other words I think the head will have to come off for the umpteenth time.
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