Author Topic: Japanese '91 3XV deresriction  (Read 2112 times)

Steveog

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Re: Japanese '91 3XV deresriction
« Reply #90 on: April 15, 2018, 10:39:27 PM »
Gentlemen -

I've been riding the 3xv in short heating cycles with ever increasing RPM, but did ring its neck once to 12K. Power is smooth from off idle to 5000 which then builds to a nice surge to 8000 at which point it jumps cleanly and enthusiastically to 10,500, then flattens out.From everything I've read here, that sounds about right for an "R" with pipes (Dog Fight) and stock CDI box and jetting that's spot on. At this point, the plan was to take the bike to a DYNO for a benchmark reading. However, our local dyno guy is a four stroke expert, mostly with new R-1's, etc. Mellorp and others have spooked me about dyno runs done by tuners who are not familiar with these 2T's. What's next? My local expert (a retired TZ racer) recommends a "Plug Chop" to see what's going on. I know what to look for, but wondering if there's any other form of VooDoo I'm missing to be sure we're getting all we can in the bike's current form. I have yet to ride any real corners, as the bike is not street legal and the track is about 1.5 hours away. If this seems all good, then some easy track time seems obvious. Opinions?   
Brief, fleeting Glory. Which of itself cannot last, but while it does is the greatest game of all.

Warwick

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Re: Japanese '91 3XV deresriction
« Reply #91 on: April 15, 2018, 11:16:37 PM »
A few plug chop runs would be useful to see how it's fuelling under load. Assuming all looks OK there, I'd be inclined to just take it to the track and get a good feel for it as is, personally. A bone stock 3XV is plenty of fun on the track, and if the track is more curves than long straights, it might even surprise you a bit as a stock 3XV has nce, flexible power and should handle quite nicely if all is well with the chassis and runing gear.

A simple dyno power check run would give you a nice baseline to check against as you develop the motor further, later. If it's running the oil pump, even an operator more used to four strokes is unlikely to cause any damage really. If it's running pre-mix, just let the operator know to not let the drum push the engine on a closed throttle after the run (blip the trottle with the clutch in on the run down etc.) If the operator is the obliging type, maybe ask if you can run the bike on the roller yourself?

In its current guise, the restrictive stock porting and ignition are the factors holding it back above 10.5k, and there's no real voodoo you can perform to get around that I'm afraid. Checking everything is as healthy as possible in terms of the motor, chassis and running gear though will allow you to make the most of it until you get around to de-restricting it fully.

Enjoy!   (-P)
Still Smoking...

Steveog

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Re: Japanese '91 3XV deresriction
« Reply #92 on: April 16, 2018, 02:00:26 AM »
Thanks Warrick - The injection pump is still intact and we have no plan to remove it. I've only use "mix" on my ancient RM80. The dyno-op I would be working with owns the biggest bike shop in our area. He also races "Expert Superbike" in the WERA series here in the US. (Second only to Moto-America, which used to be the AMA series seen in "On Any Sunday"). He knows what he's doing. Thanks for talking me down. I believe "Plug Chops" and riding our 3xv with care at the track is the best answer. I posted a diagram of the track earlier in this thread. It has a lot of everything. Long straights, interesting, tricky corners, fast sweepers and one hairpin leading to the grandstand straight. I just need to avoid the temptation to stretch the throttle on an engine that is supposed to be "fresh". Tough to do, but at my age (67) patience "should" be easier than when I was 25. 

The 3XV runs great and I just don't want to "Fook"it up. Steering input is telepathic, without any twitchiness. Of course, as I said, I haven't challenged any real corners, yet. We have a large agricultural park near our shop that we've been using for testing. But, that's nothing like a great back-road, let alone a racetrack.

Any other opinions are welcome. I've got one week from today before we go to the track. If Warrick has offered the final word on how it "should" be, I'm also open to any other thoughts about how to deal with this first track day.
Brief, fleeting Glory. Which of itself cannot last, but while it does is the greatest game of all.

thump566

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Re: Japanese '91 3XV deresriction
« Reply #93 on: April 22, 2018, 10:26:11 AM »
No, there's no English language manual I'm afraid- the 3XV was only ever sold new in Japan. You'll find links to the Japanese manuals and parts books in the resources section. Main measurments, specs and part numbers etc. are in universal 'English' script so it's fairly easy to work with them really.

Good idea to get a base dyno reading as soon as you can. That way you will be able to clearly measure the effect of any mods as and when you make them  (-P).

Hi Warwick.

Recall a few years back a UK mag featured a nut and bolt restoration of a 3XV done in Marlboro livery with black wheels. Think the guy either worked at / owned a bike dealership in SW England ? Anyhow, recall his other half was Japanese and had translated a fair part of the 3XV to assist with the rebuild so I tried to email him and request a pdf copy emphasising that it was for personal use only to assist with my rebuild and that I would in no circumstances sell "his work" without his permission but received no response to my email.
Quite understand as he didn't know me from Adam but perhaps you may know him from the forum and have better luck than I? :-\
Still firing on two.