White Bros XR4 Rev Kit

[xrsforever]

The SRC brace is the best single mod you can do to an XR.Be forwarned you will need a fender brace after cutting the front fender cause it flops around too much. I think the SRC brace cost me $ 199,the fender brace $15,buy them both.You need to tap(add threads to the top of the bottom triple crown or drill out the front fender bolts on the fender brace,good support at SRC,:cool:

 

[michman]

Before all the engine mods, but with the pumper carb I have gotten 55 miles with the A-loop tank not sure with the new mods through only have gotten to ride twice since having done all the work to the bike.

The SRC fork brace is awesome it made the bike handle some much better. No more fork flex when hitting corners with a vengence.

Put the Rev kit on tommorrow will ride Sunday and Monday. Thhis will be the last time I getr to ride my bike until dirtweek. I will fill all inMonday.

Mike

 

[Handl-it]

A loop guys, have you ever filled your empty tank to see how much it really holds? Mine holds 1.98 gallons filled to the very top of the rim. Now how far can you go before you run out? I think my Mikuni carb is a little bit better for mileage than the stock carb on the trail. On the advance issue has anyone tried to just advance the stock timing a few degrees?

 

[michman]

I put the rev kit in Saturday and rode sunday. First I thought the directions could be alot better than they were but after redaind them about five time over finally got it. One other thing is that the pick up unit looked like it was hand ground to fit the XR4 and had to file and use the dremel to get the air gap correct.

First let me strat off by saying that I only have been able to ride my new motor set up 3 times before doing the Rev kit and I am also trying figrue out my gearing.

I did notice it did take away some of the bottom end that I had before and it did make it a smoother transition to the mid range. Before it was was a massive hit right of the bottom and that I like but I miss so of the bottom end power. I really don't think it makes the bike rev that much higher if at all, just by the seat of the pants of course it seemed to rev out just like before. In the instructions it said it would rev to 11,500 but that is a bunch of crap.

All in all I would make this the last mod that you would do if at all. I would make may first the pumper carb that one thing alone will make the bike in more ways than any other mod you will do to the engine that of course is my opinion. Also some of the others on the subject let me know if there has been anything else that you have done to make your bike better.

One last thing on my A-Loop tank with all the engine mods I lost 10 miles of gas miliage per tank. I used to get around 55 miles now I had to go on reserve at the 45 mile mark and the parking lot was 1 mile away and I am not sure how far I can go on reserve.

If you have any more questions please asked.

Mike

 

[mtngoat]

Thanks Michman.

Handl it, I had thought the same thing. On my CJ7, I was able to significantly improve performance simply by advancing timing (but not too far), which is suggested by the manual for higher altitudes. I asked the same question of the White Bros. (what about just advancing timing?). He said that the timing couldn't be advanced without causing serious kick-starter "kickback". That's why the initial advance is left the same and the curve is changed somewhat.

 

[Handl-it]

So if you could adjust your timing, you wouldnt have to but a kit? I just cut a gray wire off my Wr250f to make it run better, so why not bump the Xr timing up to see what happens. Now running stock pipe, vortip, Mikuni carb with 127.5 main jet, Uni filter, air box opened up, and 10 to 1 compression piston. Stock tank gets about 60 miles before reserve. We always used to chage timing on the cars up here by 2 degrees for the altitude. The Honda starts so easy now serious kickback sould take lots of timing advancement. Anyway I will give it a try to see what happens. As the Toolman says " More Power"

 

[Shaw520]

Guys, having some experience with getting these bikes to make power, IMO the big bore kits will yeild the best HP to dollar ratio, without taxing the valve train, and without exceeding the normal rpm range. And, in the same price range. Changing the cam, and rpm range will put a limit on reliabilty and longevity.
Also,..with the bore kit, the only real necessary item to go along with it would be a pipe and silencer. After that,...a pumper carb and polished ports only make it better!

 

[mtngoat]

Shaw, I took the long analysis route, but I'm coming up with about the same conclusion. Oh well, learned something in the process.;)