90 VTR250 Trackbike or bust

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Re: 90 VTR250 Trackbike or bust

Postby Spoot5 » Sat Feb 03, 2018 2:24 pm

Hi all, I'm back at it!

John, you were right with the arm being bent wrong on the carbs. It was dragging. Thank you!

I just got back to the project. I had a few life set-backs and have finally gotten on a roll again.
Wife quick her job and then I had an L4-L5 disc bulge out in my back 3 times....that was bad.
Lots of physical therapy, no injections and I'm mostly back to normal.

I did find a 88-90 service manual in great shape, ebay.
Ordered a chinese petcock and gas cap.
Throttle cables snap back properly.
New fuel lines in. New crankcase breather hose - cleaned out collection tank.
Bike was relocated to another friends kitchen (other friend is building a new house so I had to relocate).

Friday we got it to fire up again! Its been a while since I've done anything with the VTR.
It was realy bogging on low rpm. Eventually it picked up better and as it warmed up, I was able to rev into the 8-9 range and it felt snappy!
I know I need to get it jetted and tuned, but that will come soon enough.

Next up is getting a new diaphragm for the brake res, it was all weird from drying up and freezing a couple winters.
I have some RBF600 ready for it, but just used some cheap stuff for now to get it wet and bled to test everything.
Need to get the fuel tank cleaned up inside, just a little rust. Get petcock on, get new vacuum hoses, then we can get the tank mounted.

I hope to get this stuff done by next week sunday. Then we can test ride the bike.
If that goes well, I take it in for jetting and dyno tune.

I did do the air-box mod suggested by Lord Duck Hunter. New oem air filter. De-snorkled.
http://www.rogueracing.org/vtr/airfilter.htm
'90 VTR250 Interceptor / '98 VF750F Magna / '98 VTR1000F / '08 Ridgeline / Honda Racing Bicycle
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Re: 90 VTR250 Trackbike or bust

Postby Spoot5 » Sat Feb 03, 2018 5:53 pm

I have the stock 1990 rims and so far I'm looking at a Pirelli SC1 110/70 front and a SC2 120/70 rear?
or maybe a Rosso II 130/70 rear?
hmmmm

Looks like I need to get a different rear sprocket as well to make up for the shorter tire? maybe a 46T (I have a 428 chain)


I'm working my way through Spot's build again to refresh me on everything, gleening some good data for my build. Thanks Spot !!!
'90 VTR250 Interceptor / '98 VF750F Magna / '98 VTR1000F / '08 Ridgeline / Honda Racing Bicycle
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Re: 90 VTR250 Trackbike or bust

Postby Spoot5 » Sun Feb 25, 2018 10:54 pm

Well, I spliced in the replacement Reg/Rec from an FZ1! It's the mosfet FH style, with new connectors.
Installed brand new battery, from Amazon.
​​​​​​​We started the bike up again and checked the voltages, all seemed to be doing well.
I put in the new diaphragm for the brake master - fit perfect.
We filed/sanded off the rough edges on the airbox mod, so hopefully the air flows smoothly into the airbox.

Next, do some more front brake bleeding and get the rear brake pedal mounted and ready.
Also need a couple foot pegs.
Then, off for tuning...
'90 VTR250 Interceptor / '98 VF750F Magna / '98 VTR1000F / '08 Ridgeline / Honda Racing Bicycle
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Re: 90 VTR250 Trackbike or bust

Postby Spoot5 » Mon Mar 12, 2018 7:24 pm

well, took the bike to the dyno.
it hit a WHOPPING 18hp !
it climbed nicely to about 8,500-9,000rpm, then it just bounced and it never went higher.
they said the rear carb was leaking gas. I think the front carb-boot clamp was a little loose as well. uhg.

So, we took the carbs off again, will clean and I have a Factory Pro kit on order.
'90 VTR250 Interceptor / '98 VF750F Magna / '98 VTR1000F / '08 Ridgeline / Honda Racing Bicycle
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Re: 90 VTR250 Trackbike or bust

Postby squirrelman » Mon Mar 12, 2018 9:39 pm

Did you test-ride the bike ? :roll: Notice very low power ? :cry: seems like one cylinder isn't working ? :o why a dyno run if it obviously wasn't running right ? :?:
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Re: 90 VTR250 Trackbike or bust

Postby Spoot5 » Wed Mar 14, 2018 8:24 pm

It seemed to be running ok. buddy took it for a short run, he said it felt ok.
It would have been obvious if it was missing one cyl.
It rev'ed up nice on the top, so I thought it was good to go.

jet kit should be here friday, then I'll clean and re-do the carbs.

here is the 4th gear roll-on
Image

here is 1st - 5th gears
Image
Last edited by Spoot5 on Thu Mar 15, 2018 2:54 pm, edited 1 time in total.
'90 VTR250 Interceptor / '98 VF750F Magna / '98 VTR1000F / '08 Ridgeline / Honda Racing Bicycle
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Re: 90 VTR250 Trackbike or bust

Postby Spoot5 » Thu Mar 15, 2018 2:52 pm

@squirrelman - I barely understand carbs, but I watched a couple videos and I think I understand a tad more about them.

What I think may be happening....
low speed rpms - the pilot jets (stock) may be clogged/dirty. It idles really poorly. Low speed revs are slow to respond.
high rpms - I think the floats are too low in the bowl and the main jets (stock) are get starved when the rpms hit 8-9k.

?

I have a Factory Pro jet kit coming today (fingers crossed).
I will put in the #38 pilots (as I've seen many others here do).
I will put in the #128 mains and put the shim on (where others have suggested).
I will clean up the carbs a little and check/adjust the floats.

I have a Yosh slipon and the airbox mod (8 holes) with new stock filter.

?
'90 VTR250 Interceptor / '98 VF750F Magna / '98 VTR1000F / '08 Ridgeline / Honda Racing Bicycle
CCS Mid-West #518 Am
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Re: 90 VTR250 Trackbike or bust

Postby squirrelman » Fri Mar 16, 2018 12:26 am

the jetkit will tell you which mainjets to try. i agree that your idlejets may be partially-clogged. dyno curves show way too much zig-zaging, supposed to be steady, gradual curves not up and down frequently. you might try taping over the airbox holes for testing purposes. expect 27-30HP if engine is right. you tried a compression test ?


the tuning instructions are key to getting best performance. remember, find best mainjet first, then tune lower ranges.
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Re: 90 VTR250 Trackbike or bust

Postby Spoot5 » Fri Mar 16, 2018 9:05 am

Thanks for the info !

I did compression test way early on. It was within the specs, I just don't recall what the numbers were at the time.
I was very surprised with them seeing the engine had sat in a garage for a few years.

I'll start with the mains and let you know....
'90 VTR250 Interceptor / '98 VF750F Magna / '98 VTR1000F / '08 Ridgeline / Honda Racing Bicycle
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Re: 90 VTR250 Trackbike or bust

Postby Spoot5 » Fri Mar 16, 2018 9:56 pm

I took the bowls off and checked the pilots. One was dirty, the other was completely clogged.
The mains looked ok. The float valve looked clean and the tiny pin moved freely.

It did have the stock #35 pilot and stock #115 main.
Back when we first rebuilt the carbs, the diaphragm thing was in great shape.
The enricher things move ok and seem to be good. I might try to spray some lube down into those cables.
I put the carbs back together but did not put them on the bike.

I had a guys night at the range. On my way there, wife txt'd me that I got a package in the mail..it was the Factory Pro kit!
So, tomorrow afternoon, I will take the carbs apart again and install the #38 pilot and maybe the #120 main and see if I can determine where to put the shims.

The fuel mix screw was 1 3/4 turns out, fyi. I watched some vids on how to adjust those, so I will do that after its all back together.

(dang, I hate carbs. lol)
'90 VTR250 Interceptor / '98 VF750F Magna / '98 VTR1000F / '08 Ridgeline / Honda Racing Bicycle
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