Piston Upgrade
Page 1 of 1
Piston Upgrade
by Flyingwheel Tue Oct 22, 2019 4:42 pm
- Wossner piston, forged aluminum piston 102mm
- Gives 680cc more or less of fire breathing power
- Shortened coated skirt
- 76 gr lighter
- Other than the difference in size, the top shares the same design as the stock
- So compression ratio should be the same.
- Was purchased from LA sleeve, complete with rings, pin and circlips for $185
- They or the machinist of your choice can bore and hone for around $80 more
- Only 200 miles on it, so not prepared to announce the mother of all mods yet, but so far money well spent
- First thing I noticed is that there is a lot more tension in the #1 & 2 rings
- I have used no oil. At steady state throttle, little vibration, get on the gas and you know it is a single however
- Yes the exhaust is louder, in a lower menacing way
- What you really notice is the increased torque between 3000 and 6500rpm, especially in 3rd, 4th and 5th gear
- Making passes, you would swear you were riding a larger displacement twin
- With some larger intake valves this would be a real fire-breather
- I will be off to DV, next week to further break it in and when I return I will do some runs on my local hill to compare roll on speeds against my prior runs on stock and pre-bore modified runs
- I have already beaten the stock run on my 2/10 mile hill in the first 100 yds before I shut it down
- Gives 680cc more or less of fire breathing power
- Shortened coated skirt
- 76 gr lighter
- Other than the difference in size, the top shares the same design as the stock
- So compression ratio should be the same.
- Was purchased from LA sleeve, complete with rings, pin and circlips for $185
- They or the machinist of your choice can bore and hone for around $80 more
- Only 200 miles on it, so not prepared to announce the mother of all mods yet, but so far money well spent
- First thing I noticed is that there is a lot more tension in the #1 & 2 rings
- I have used no oil. At steady state throttle, little vibration, get on the gas and you know it is a single however
- Yes the exhaust is louder, in a lower menacing way
- What you really notice is the increased torque between 3000 and 6500rpm, especially in 3rd, 4th and 5th gear
- Making passes, you would swear you were riding a larger displacement twin
- With some larger intake valves this would be a real fire-breather
- I will be off to DV, next week to further break it in and when I return I will do some runs on my local hill to compare roll on speeds against my prior runs on stock and pre-bore modified runs
- I have already beaten the stock run on my 2/10 mile hill in the first 100 yds before I shut it down
Last edited by Flyingwheel on Tue Oct 22, 2019 5:05 pm; edited 2 times in total
Flyingwheel- Posts : 164
Join date : 2019-10-20
Re: Piston Upgrade
by Flyingwheel Tue Oct 22, 2019 4:49 pm
Just got back from my DV trip and put about 300 more miles in my KLX680
- On steep, higher speed grades the KLX could pull away, had substanially more power to pass as highway speeds. Surprisingly, I felt my aftermarket windscreen provided better wind protection and handled wind gusts better, the KLR directed the wind back onto my shoulders and head.
These bikes are about the same size, the KLX is about 30# lighter, but felt entirely different. T
I finally redlined the KLX. Where the new piston made for a smoother motor lower in the RPM curve, above 7000 rpm it became harsh.
Guessing that the lighter than stock piston has an effect on the counter balancer at these rpm levels.
Still think it is a good tradeoff unless you routinely wring its neck
I still prefer the KLX, as I have modded it, just because of its felt lightness and flickability
It felt smoother at the speeds I ride and handled the winds better imo
- On steep, higher speed grades the KLX could pull away, had substanially more power to pass as highway speeds. Surprisingly, I felt my aftermarket windscreen provided better wind protection and handled wind gusts better, the KLR directed the wind back onto my shoulders and head.
These bikes are about the same size, the KLX is about 30# lighter, but felt entirely different. T
I finally redlined the KLX. Where the new piston made for a smoother motor lower in the RPM curve, above 7000 rpm it became harsh.
Guessing that the lighter than stock piston has an effect on the counter balancer at these rpm levels.
Still think it is a good tradeoff unless you routinely wring its neck
I still prefer the KLX, as I have modded it, just because of its felt lightness and flickability
It felt smoother at the speeds I ride and handled the winds better imo
Flyingwheel- Posts : 164
Join date : 2019-10-20
Re: Piston Upgrade
by Flyingwheel Tue Oct 22, 2019 4:56 pm
- Kawasaki Vulcan piston big bore (678cc) with a pipe
- cut air box
- a Dial-A-Jet.
- Runs on 87 gas with minimal detonation where the stock 650 piston wouldn't
- Still use 92 gas just to be safe
- cut air box
- a Dial-A-Jet.
- Runs on 87 gas with minimal detonation where the stock 650 piston wouldn't
- Still use 92 gas just to be safe
Flyingwheel- Posts : 164
Join date : 2019-10-20
Re: Piston Upgrade
by Flyingwheel Tue Oct 22, 2019 5:06 pm
Flyingwheel wrote:- Wossner piston, forged aluminum piston 102mm
- Gives 680cc more or less of fire breathing power
- Shortened coated skirt
- 76 gr lighter
- Other than the difference in size, the top shares the same design as the stock
- So compression ratio should be the same.
- Was purchased from LA sleeve, complete with rings, pin and circlips for $185
- They or the machinist of your choice can bore and hone for around $80 more
- Only 200 miles on it, so not prepared to announce the mother of all mods yet, but so far money well spent
- First thing I noticed is that there is a lot more tension in the #1 & 2 rings
- I have used no oil. At steady state throttle, little vibration, get on the gas and you know it is a single however
- Yes the exhaust is louder, in a lower menacing way
- What you really notice is the increased torque between 3000 and 6500rpm, especially in 3rd, 4th and 5th gear
- Making passes, you would swear you were riding a larger displacement twin
- With some larger intake valves this would be a real fire-breather
- I will be off to DV, next week to further break it in and when I return I will do some runs on my local hill to compare roll on speeds against my prior runs on stock and pre-bore modified runs
- I have already beaten the stock run on my 2/10 mile hill in the first 100 yds before I shut it down
update:
- 1,300 miles on the 680 big bore and I think it was a success
- Up to then I had done the normal carb and exhaust mods and replaced the airbox lid with my own prefilter design
- Never dyno'd the bike, but on my 2/10 mi. test grade, my roll ons from 50 in 5th gear have increased from 67 to 80mph
- The motor is very smooth and the power increase is noticeably better in the 65-85 mph range
Flyingwheel- Posts : 164
Join date : 2019-10-20
Page 1 of 1
Permissions in this forum:
You cannot reply to topics in this forum|
|
|