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Discussion Starter · #1 ·
Its been a long time coming but I think im pretty close to pulling the trigger on a 719 bb/piston kit and getting some more power of course but also while getting better overall topend performance with a (still) lighter piston than stock. I say "I think I am" though because my question is: if I upgrade to a 719 now, and in the future drop in a stroked crank (say 15-25k miles later), will this cause any issues in terms of wear patterns? It seems that of the 5 or 6 people I've talked to about this (all engine builders i.e. m tech, EM, a local motor machinist, crankworks in AZ), the opinion on this questions is 50/50 split. But their opinions are strongly one sided and insistent that this either will be not an issue at all to separate the mod over time, or that it could be problematic in swapping the crank later versus swapping it at the same time as the piston kit/bb. What are your opinions on this and why? To my knowledge, the 719 kits out there use a stock connecting rod, which at the time of swapping the crank I would likely change this if not for a new rod ratio to complement the new stroke, but also to go for a higher quality forged rod as well. Im no engine builder or subject matter expert, id love to get some good input and nothing along the lines of stating what I should I do, but looking for the why. Thanks
 

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Just wondering; what's your goal and expectation? If more power dominates, doubt even a 719 stroker would approach the output of several factory bikes of similar displacement available today (e.g., KTM690, Husaberg 701, etc.).

if you're building, "The World's Fastest KLR," (q.v., The World's Fastest Indian), then maybe a bored-and-stroked KLR is the only way to go.

Otherwise . . . 719 stroker with stock-length connecting rod? Interesting concept!
 

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Discussion Starter · #3 ·
Honestly, its a matter of time before I get a gsa (not in lieu of my klr though). Im not trying to pull off some fastest klr build but I do simply love my klr and i love the carb'd single, and I do want more power. The 719 bb is a +5mil over stock bore and its this big bore kit that is used in conjunction with a +5 mil stroke in order to pull off 762 cc's of displacement. So my approach is to do the BB kit now, and then perhaps when a +5 mil stroked crank is available off the shelf in the future I can swap with mine as a core to install later down the road.
 

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Discussion Starter · #4 ·
Honestly, its a matter of time before I get a gsa (not in lieu of my klr though). Im not trying to pull off some fastest klr build but I do simply love my klr and i love the carb'd single, and I do want more power. The 719 bb is a +5mil over stock bore and its this big bore kit that is used in conjunction with a +5 mil stroke in order to pull off 762 cc's of displacement. So my approach is to do the BB kit now, and then perhaps when a +5 mil stroked crank is available off the shelf in the future I can swap with mine as a core to install later down the road.
As for the specs for a connecting rod, I dont know what I might use for that yet, but I do know I would make it a stronger material regardless of whether or not I change the rod ratio.
 

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Without head work your compression ratio is going to be very high.
If you port the head, add a little volume to combustion chamber, now your flowing more air than the stock carb can move.
It really opens a rabbit hole when you start pushing this far.
And its still not gonna run with a T7, AT, or 701.
I'm not being negative just offering an opinion.
By the time you've spent this much and your reliable KLR is no longer reliable, I would rather keep my 685 and get a AT as a second bike.
I rode the TAT in July with 2 T7s and an AT, my Cogent sprung pig kept up in the dirt but on the twistys the AT is a beast.
Good luck on your build, I hope it meets all your goals!
 

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I say "I think I am" though because my question is: if I upgrade to a 719 now, and in the future drop in a stroked crank (say 15-25k miles later), will this cause any issues in terms of wear patterns?
Of course it will! The question is, will a light glaze breaking hone eliminate the OLD pattern after 15-25k miles?
If you are dead-set on stroking the engine, do THAT first! It will yield MORE Torque, regardless of the current bore size!
And easier to over-bore later.

Too many owners put on a LOUD exhaust, before they open up the air box. THAT is also 'Backwards'!
We need to get more air IN, Before we Can get More air Out!

The cylinder head ports need to be massaged BEFORE either line of 'attack' will yield its full potential!
Total air flow thru the running engine makes more difference than the basic engine size, IME.
 

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I do NOT think that that is possible!!
The stock piston already has a high ring stack and wrist pin. I doubt you could raise the wrist pin enough to keep the stock rod if you stroke the crank. And I have no idea where you would get a stroker crank fir a KLR.
 

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If and when a stroker crank is available, I'd worry about it then......and I wouldn't bother with any of that myself, that's a huge amount of work and expense to try (and fail) to make a KLR faster than a KTM.

I'm sure that a jet kit, airbox mods, silencer and a 719 BB kit will fufill your desires for a bit more power and if it doesn't, neither will a stroker kit/crank. Even porting/valves and cams are relatively easy.

2 cents,

Dave
 

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I did the 705bb , ported the head, added bigger valves, opened airbox, aftermarket exh, camshafts and carb work. Does it have more zip? Yes. Does it run with 790,AT, Yamaha 700? Well the first two i can hang with from dead stop to about 70mph. After that adios their gone and keep going. Lol. But after all the mods im still 5-6 grand less money into bike. So if you like to have your own personal twist of a bike. Go for it.
 

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I did the 705bb , ported the head, added bigger valves, opened airbox, aftermarket exh, camshafts and carb work. Does it have more zip? Yes. Does it run with 790,AT, Yamaha 700? Well the first two i can hang with from dead stop to about 70mph. After that adios their gone and keep going. Lol. But after all the mods im still 5-6 grand less money into bike. So if you like to have your own personal twist of a bike. Go for it.
Dear Steve,
You mentioned added bigger valves, camshafts and carb work.
It is possible to learn from what bike (or place) youve got the valves, cam shafts from? Also done to the carb.
- Have a KLX650C -93 and I'm living in Sweden, so little harder for me to get parts from US.
Much appreach in advance
 

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Have a KLX650C -93 and I'm living in Sweden, so little harder for me to get parts from US.
Much appreach in advance
In regards to the performance parts you inquired about, the KLX650 engine is Entirely different than the KLR650 engine.

Performance parts for the KLX650-A (93-95) and KLX650-D (1996 only for a USA model, don't know about other countries) series 'Dirt Bikes' would work in your KLX650-C series engine.
 
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