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Rebuilding my xr4

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Hi everyone, I'm thinking of tearing down my xr over the winter and rebuilding the engine a little as well as getting the frame painted seeing as she's at about 8,000 miles and want to keep her well maintained.

I want to keep the bike as reliable as can be as I use her quite often, but would like a little more power out of the engine without compromising much.

I'm thinking of installing:

hot cams stage 1 cam

wiseco cam chain

wiseco valves

kibble white springs

wiseco lite weight stock bore piston (depending on how the stock piston looks upon inspection)

rebuilding the rocker assembly and replacing anything that could be damaged

replacing the stock carb with a mikuni pumper carb.

Anyone have experience with mods like these? Should I worry about the con rod as well? I also don't want something the clutch won't be able to handle either. I've heard of others needing to install spacers to increase tension on the springs and then they blow through them really quick.

I'm more worried about reliability than power, and want to get the best of both worlds with this build.

THANKS!

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Hi everyone, I'm thinking of tearing down my xr over the winter and rebuilding the engine a little as well as getting the frame painted seeing as she's at about 8,000 miles and want to keep her well maintained.

I want to keep the bike as reliable as can be as I use her quite often, but would like a little more power out of the engine without compromising much.

I'm thinking of installing:

hot cams stage 1 cam

wiseco cam chain

wiseco valves

kibble white springs

wiseco lite weight stock bore piston (depending on how the stock piston looks upon inspection)

rebuilding the rocker assembly and replacing anything that could be damaged

replacing the stock carb with a mikuni pumper carb.

Anyone have experience with mods like these? Should I worry about the con rod as well? I also don't want something the clutch won't be able to handle either. I've heard of others needing to install spacers to increase tension on the springs and then they blow through them really quick.

I'm more worried about reliability than power, and want to get the best of both worlds with this build.

THANKS!

 

ditch the wiseco cam chain and put a OEM crf450 one in there its much cheaper and stronger than the stock one. Replace the cam chain tensioner while your at it they all break eventualy and can cause major engine damage. I doubt that you wil have any rocker damage 8000 is really not a lot of miles for this bike. the pumper carb is ment to be the best mod for these bikes what i would suggets is that you preform a compression and leak down test write down the numbers as a starting point and to evaluate your rebuild. Then just do new rings/piston valves and pumper. Honestly I dont see the point in  chaseing power in the xr400 its got plenty for the kind of bike it is with the suspention set up it has, and its main selling point is the reliability of the machine but hey each to there own. If your chaseing power i would suggest that you sell the bike and go for a more modern platform.

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I agree with everything the above poster said except for the newer platform for power. While it's never gonna be a powerful bike to kill 450's, having extra power on the trails is always handy, especially when you can blow past the 450's in the snotty tight stuff.

If you want a cheaper carb option, try the bst40 or bsr42 mod in ATJ's thread. It's pretty good bang for buck and offers similar throttle response to the pumper.

Also, with the rod and clutch. If the rod has no excessive movement I wouldn't worry about it. And with the clutch, I'd just source some heavy duty clutch springs.

I would also recommend upgrading the suspension to suit your weight and riding style.

Edited by Dave2233

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Should have mentioned. I don't use it on the trail. It's a supermoto I use on the street. Suspension is already set up for this application. Already had my cam chain tensioner fail too, and put in a tokyomods manual tensioner.
I've seen others post a lot of positive things about the stage 1 cams, but I don't want to bother with that if it will be a major sacrifice in reliability

I'm also the fourth owner, so 8,000 is just a guess. Had 5,000 on the odometer when I got it (also meaning 5000 miles since motard conversion) Not sure how much it was ridden before this, or how hard

 

Thanks again!

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Should have mentioned. I don't use it on the trail. It's a supermoto I use on the street. Suspension is already set up for this application. Already had my cam chain tensioner fail too, and put in a tokyomods manual tensioner.

I've seen others post a lot of positive things about the stage 1 cams, but I don't want to bother with that if it will be a major sacrifice in reliability

I'm also the fourth owner, so 8,000 is just a guess. Had 5,000 on the odometer when I got it (also meaning 5000 miles since motard conversion) Not sure how much it was ridden before this, or how hard

 

Thanks again!

 

if its a supermoto disregard the bit about chaseing power and go for it!

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The xr400 is a good sumo platform. I have a sumo setup for mine that I recently swapped the dirt kit back on for enduro season. If it's strictly a sumo, look at getting the flywheel lightened for that top end power. I thrash on my xr pretty brutally and she holds up well.

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For street use, I'd get a stage 2 cam. More mid and upper power for pulling through the gears.

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