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Stroker + e-start

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First off, I am not a mechanic, but I know a guy that builds some pretty extreme stuff for pro hill climbers (bike and sled). He's great with engines and building what people want. He just finished stuffing a turbocharged YZF1000 motor into a Polaris Razor. So, I will not be doing this work, but will be providing all the parts for the build to a very competent builder.

What I want to know is if anyone has done this or knows someone who has done this. Here is the plan.....

My 96 XR400 is in dire need of a complete motor rebuild. I have also been wanting to do an e-start to the machine using the trx400ex parts. I love my XR, it has become a part of me over the years, but I am almost 47 with 3 knee surgeries to the kickstarter knee :thumbsup: and would love the option of the magic button. Thanks to e-bay I have all the e-start parts except the actual starter motor and the 400ex crank :ride:.

I have a stage 2 hotcam in it already and a BSR-42 carb. I want to redo the head with oversize Kibblewhite valves, and punch the cylinder out to a 440 since I will have to split the cases for the 400ex crank anyway. I have recently found out that HotRods makes a stroker crank for the 400ex, which, for about $240 more, would take the motor up to 460cc :ride: (insert Tim the Toolman grunt here).

Has anyone done this? Is it going to seriously compromise the motor to do this to it? I don't ride in a hot area, and I ride at elevation most of the time in technical terrain where luggability (if that is even a word) is key to my riding style. There are times however when things really open up in some of the high mountain prairies, and you want to have the power to open it up and go :banana:.

I'm just looking for a little feedback before I start this project. It will probably be strung out between now and next spring, but I want to get started getting parts together now as I can afford it, and have the work done over the winter months.

Thanks for any feedback guys. My main decision at this point is to stay with a 440cc big bore, or stroke it out to 460cc. Any other opinions about upgraded CDI boxes, starter motors, wanting to come ride it when it's done, are always welcome.

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would it not of been easier to buy a complete ex engine and fit it into your bike theres this on on ebay us http://cgi.ebay.com/ebaymotors/HONDA-400EX-440-BIG-BORE-MOTOR-ENGINE-01-00-EX-TRX450-_W0QQcmdZViewItemQQhashZitem27bc59f233QQitemZ170663735859QQptZMotorsQ5fATVQ5fPartsQ5fAccessories might be quicker and cheaper in long run but i guess you already spent a bit on the parts you already have .

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Apparently there are some slight differences with the complete motors that make modifications necessary to mount them in an XR frame. It can be done, but not without some work. I also wanted to keep the kickstarter which the trx400 doesn't have, and I didn't want a reverse gear either. Could be a fun novelty, but not what I want.

Even with buying a good bottom end with all the mechanicals needed, you still need all the electrical off the trx400. (harness, stator, rev box, coil, starter solenoid, ignition switch, start button, and rectifier)

I've got less into it by being patient, and shopping. I will install all the electrical myself with my mechanic only doing the internals in the motor. The parts he will have to install would all have to be removed and re-installed anyway with the big bore, so having him change out to the trx400 parts won't be any more cost to me. With him doing the work I also have an excellent mechanic that backs his work doing it right the first time and I don't have to worry about the unknown of a complete motor bought on e-bay.

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i love the idea just a couple questions. why not freshen up the 416 with a stroker crank? what cc would that give? would that be a quicker revving motor than a 440 with a stroker crank? why i ask is because you mentioned compromising the motor, why not keep it at 416 where it has a pretty safe cylinder wall and add a stroker crank?

First off, I am not a mechanic, but I know a guy that builds some pretty extreme stuff for pro hill climbers (bike and sled). He's great with engines and building what people want. He just finished stuffing a turbocharged YZF1000 motor into a Polaris Razor. So, I will not be doing this work, but will be providing all the parts for the build to a very competent builder.

What I want to know is if anyone has done this or knows someone who has done this. Here is the plan.....

My 96 XR400 is in dire need of a complete motor rebuild. I have also been wanting to do an e-start to the machine using the trx400ex parts. I love my XR, it has become a part of me over the years, but I am almost 47 with 3 knee surgeries to the kickstarter knee :thumbsup: and would love the option of the magic button. Thanks to e-bay I have all the e-start parts except the actual starter motor and the 400ex crank :ride:.

I have a stage 2 hotcam in it already and a BSR-42 carb. I want to redo the head with oversize Kibblewhite valves, and punch the cylinder out to a 440 since I will have to split the cases for the 400ex crank anyway. I have recently found out that HotRods makes a stroker crank for the 400ex, which, for about $240 more, would take the motor up to 460cc :ride: (insert Tim the Toolman grunt here).

Has anyone done this? Is it going to seriously compromise the motor to do this to it? I don't ride in a hot area, and I ride at elevation most of the time in technical terrain where luggability (if that is even a word) is key to my riding style. There are times however when things really open up in some of the high mountain prairies, and you want to have the power to open it up and go :banana:.

I'm just looking for a little feedback before I start this project. It will probably be strung out between now and next spring, but I want to get started getting parts together now as I can afford it, and have the work done over the winter months.

Thanks for any feedback guys. My main decision at this point is to stay with a 440cc big bore, or stroke it out to 460cc. Any other opinions about upgraded CDI boxes, starter motors, wanting to come ride it when it's done, are always welcome.

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i love the idea just a couple questions. why not freshen up the 416 with a stroker crank? what cc would that give? would that be a quicker revving motor than a 440 with a stroker crank? why i ask is because you mentioned compromising the motor, why not keep it at 416 where it has a pretty safe cylinder wall and add a stroker crank?

The 416 (87mm piston) with the stroker crank takes it to a 440. It is a consideration to keep it there if going to the 89mm piston will create more problems. My thought was if I'm going to have to pay to have the cases split to change out the crank, I might as well do the big bore while I'm in there, if it's not an issue. I'm reasonably sure that a stroker crank will slow down the revving a little, but I'm not sure if there would be a difference in that between the 87mm and the 89mm piston. I'm not as concerned about quick revving as I am about just having the power to lug it through the technical stuff and still have enough to get my 260lbs. (with gear) up to speed in the open stuff when I'm at 8000-9000ft.

Edited by Draybob

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The 416 (87mm piston) with the stroker crank takes it to a 440. It is a consideration to keep it there if going to the 89mm piston will create more problems. My thought was if I'm going to have to pay to have the cases split to change out the crank, I might as well do the big bore while I'm in there, if it's not an issue. I'm reasonably sure that a stroker crank will slow down the revving a little, but I'm not sure if there would be a difference in that between the 87mm and the 89mm piston. I'm not as concerned about quick revving as I am about just having the power lug it through the technical stuff and still have enough to get my 260lbs. (with gear) up to speed in the open stuff when I'm at 8000-9000ft.

may i ask what the math is to figure out what cc you will have after the crank? i have a 426 and kinda curious what it will be after the crank; would it be a 450?

i weigh 235(probably 260 with pack and gear) so i hear ya about the open stuff but i am higher in elevation. my home is 8300 and i only go up from there. any where from 8k to close to 13k so i wanna little more in the open as well. just not sure if i can spend any more money on the xr. i can buy a fun 2 stroke for more power if i need for about twice the money including labor of installing the stroker crank. oh the xr is the most fun money pit ever. :thumbsup:

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The math is: bore(cm) x bore(cm) x stroke(cm) x .7854

The stroker crank for the XR or TRX adds 4mm to the stroke. The stock stroke on an XR400 is 70mm, so with the stroker you would have 74mm. Then all you do is move your decimal point one to the left to convert everything to cm and plug it into the formula. That does come out to almost exactly 450cc.

Edited by Draybob

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I would just do the 440,done right it will have low end like a tractor.If you stroke it, it will give you more low end that you dont need.Also even more reduce top end.Also hard on the clutch.If your over 200 hunred pounds,will slip in top gear.You will need hinson clutch basket,hd springs.

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Copying graphs is always difficult, so I hope it lines up...

Bore---- Stroke---vol. cc

85------ 70----- 397.2151211

85.5---- 70----- 401.9019847

86------ 70----- 406.6163372

86.5---- 70----- 411.3581786

87------ 70----- 416.1275089

87.5---- 70----- 420.9243282

88------ 70----- 425.7486364

88.5---- 70----- 430.6004336

89------ 70----- 435.4797197

89.5---- 70----- 440.3864947

Stroker

85------ 74----- 419.9131281

85.5---- 74----- 424.8678124

86------ 74----- 429.8515564

86.5---- 74----- 434.8643602

87------ 74----- 439.9062237

87.5---- 74----- 444.9771469

88------ 74----- 450.0771299

88.5---- 74----- 455.2061726

89------ 74----- 460.3642751

89.5---- 74----- 465.5514372

Perc

Edited by Perc82
Alignment

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I did some research on xr4 stroker cranks couple months back.

First not sure the difference when using trx parts but xr4 strokers use a custom piston with shorter pin to deck height. Not just your standard off the shelf xr piston.

Powroll's is 87mm making xr440. Did not find another size made else where. JE will custom make but min amount.

Pam at Powroll for lack of a better term talked me out of it. "Cannot use their "tough rod" on the xr crank, Stock rod has been known to fail on some stroked motors (Tapered top believed to allow more oil up and in, fails), They will not touch a Hot Rod rod, Her and i having a history (used them for many of my vintage racers over the years) and she also metioned it does require high octane and w/ the far and away destitations of my DS rides may also be cause for concern."

just my rambling contribution cause its late and i'm tired.

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Oh and curse you BTR for bringing up the "clut_h" word. 250lb plus gear and just putting my fresh Big bore and bsr42 back in the frame, all the while not wanting to look in the direction of the next thing to fail. Was hoping the money tree would harvest before the clutch goes.

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You should use barnett clutch springs with 440 kit.Alot more power can be had with the right big tube header,muffler,air box mod combo.Have a good ride ADITD

I have Barnett springs, Supertrapp 12 disc, Have 2 air boxes (both snorkels pulled and uni filter, 1 has UNI 1" air vents drilled in it and one not)... The header is where i have gone back and forth? Loss of torque vs Hp gain... stock with welds ground now.

Look forward to ridin down south with you one day.

Sorry for the Hijack OP. If you want i will pm you what info i found.

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Im ready to ride anytime,I use the pro vents about 5 per side.Also uni 1985 xr 500 air cleaner.Also a big tube header works well with 440,and big core muffler.

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