Author Topic: Racer Resurrection  (Read 27685 times)

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Offline BRT-GTR

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Re: Racer Resurrection
« Reply #40 on: August 29, 2015, 11:41:20 AM »
   Al,     Re:- Port height / air leakage.

         A couple of weeks ago I cleaned up the crankcase intake ports on a standard GTR engine, just took the lumps off and smoothed them out , no increase in size at this stage. The metal land at the top edge of the port is only 1 to 1.5 mm wide which seemed very narrow for sealing purposes. However, thinking it through, at the critical time in the compression of the crankcase gases, the valve is fully closed and gets pushed outwards onto the valve cover and  I think this is where the seal is made. Even there , adjacent to the intake stub, there is only 3mm of flat surface on which to seal.
 
   It would be interesting to pressure test the disc valve seal but I don't have the kit. The valves do obviously seal effectively, I'm not aware of any reports or signs of blowback through the carbs but then I've never raced one.  So maybe a combination of close tolerances, oil film and gas inertia work together to seal the intake ports in a similar manner to the crank centre labyrinth seal.
    As long as there is some metal at the top edge of the port I wouldn't worry too much about the port height.
      Brian.
Growing old is compulsory, Growing up is optional.

Offline al_pritchard

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Re: Racer Resurrection
« Reply #41 on: August 31, 2015, 12:01:29 PM »
- Paul,

Yea it the AirTech faring and tank. Pretty happy with the tank so far. But I’m just starting to look at how to get it mounted. It doesn’t use the two rubber pucks by the neck, but has two threaded bungs about 5in back from. I guess I’ll look at making two tabs on the side of the frame rail and bolting it down.


- Karl,
Yea I thought about JB weld, and a friend brought up another product. Cant remember it, but it’s basically an epoxy product, but with an aluminum base.


- BRT-GTR,
Thats a good point.



On another topic, who is showing up to NJMSP this month for the Garden State Classic?
Al Pritchard
Highlands, NJ

BS175 Racer

Offline bsracer

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Re: Racer Resurrection
« Reply #42 on: September 01, 2015, 02:04:38 AM »
Devcon.

paul

Offline craig641

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Re: Racer Resurrection
« Reply #43 on: September 04, 2015, 02:54:08 PM »
Al,  I plan to be there with my Bridgestone race bike. Stop by and say hello.
Craig

Offline OldSwartout

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Re: Racer Resurrection
« Reply #44 on: September 05, 2015, 06:45:25 AM »
Craig, I see you won the 200GP class at NJMP both days.  I assume that was on the Bridgestone.  Congratulations.
Karl Swartout
Mooresville, IN
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BS350 GTR

Offline craig641

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Re: Racer Resurrection
« Reply #45 on: September 07, 2015, 05:08:12 PM »
Thanks Karl.  When she runs, she runs real well.  When she doesn't she's horrible.  I backed up my four wins at New Jersey with a miserable weekend at Mosport. I had two broken cylinder studs on Friday.  Followed by a dead battery in one heat race on Saturday and then a connecting rod bearing gave up in my second race on Saturday.  Along with a couple of overcooked pistons.  And I just got back from a race at New Hampshire where I couldn't even get my bike to run for more than about ten seconds.  I'm almost ready to throw in the towel on this thing.

Offline OldSwartout

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Re: Racer Resurrection
« Reply #46 on: September 07, 2015, 07:28:39 PM »
There does seem to always be issues with the old two-strokes when trying to push them so far.  I used to race a production GS450 Suzuki in WERA back in the day; it was nice to be able to just go race without something to rebuild between race weekends or sometimes between practice and a race on the same day.  Back then, you just had to tape over the lights and go race, so you could ride the bike on the street during the week (which I did).  The only time I ever wrecked that bike was on the street, not on the track.   ::)
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

Offline bsracer

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Re: Racer Resurrection
« Reply #47 on: September 08, 2015, 09:27:10 AM »
I made it 6 laps on Fri practice at Miller before the big end bearing went. I think I had the timing too far advanced since before Willow.

paul

Offline vinny g

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Re: Racer Resurrection
« Reply #48 on: September 09, 2015, 03:30:43 PM »
There's no reason why a Bridgestone can't be both fast and reliable.We have no real issues over with them over here and do no more than basic checking and maintenance.In 15yrs i've never had one seize.Over the last few years a broken ignition wire and a snapped stud are my only dnf's.

Make sure you press your cranks up so the big end's are exactly in the centers of the bores.I've measured a few that press together a mm or so out and that will fry a big end as the rod/bearing scuffs the crank cheek.

Use a quality 2 stroke oil..and plenty of it.Go fully synthetic at 27:1.

We used Bridgestone standard cranks reliably upto 11000rpm and 32 rear wheel bhp.

Watch for air leaks on the crank drive side..it's possibly to get a leak along the splines and drive gear.Clean the outer face of the gear..smear with silicone..smear along the splines..fit flat washer..fit nut..tighten.A smear on the faces of the bush will do no harm either.

I don't run paper base gaskets,the mating faces aren't wide enough.Once you know the thickness you require make them in alloy or steel.Silicone both sides..Threebond is ok.

If using a standard LH discvalve housing only run a single lipped seal.A double lipped leaves the outer un-lubed without an oil pump and it will overheat the seal.

Vince

Offline vinny g

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Re: Racer Resurrection
« Reply #49 on: September 09, 2015, 03:33:21 PM »
Oh..and a 6mm hole in the piston skirt just below the ring land inline with the rear boost port will vent hot gasses and keep the piston crown cooler.

Offline bsracer

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Re: Racer Resurrection
« Reply #50 on: September 10, 2015, 10:09:32 AM »
Thanx for the input Vince. I usually run Maxima 927 Castor at 28:1. Have aluminum shims for base gaskets. Never had an issue with the LH seal but will look it over. I also seal the RH gear as I noticed leaks when pressure testing in the past. This was strictly my fault for not being thorough. I advanced the timing a couple of races ago along with another change. That change didn't work and I didn't move the timing back. This time out, again the bike showed signs of being rich. The change to 32:1 did not seem too drastic. The fact that the timing was still advanced did lead to the big end failure. I still consider to have never "seized". Bores in good shape . The crank locked solid on the bearing that failed. Very interesting to see the bottom end, the cylinders and the head completely dry of oil and no real damage aside from the big bearing. I will have it back together for the next race at Barber in Alabama in October, with a little more attention to detail.

paul

p.s. keep me posted on those parts Vince!

Offline al_pritchard

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Re: Racer Resurrection
« Reply #51 on: September 22, 2015, 09:36:42 AM »
Paul - Thats the stuff I was thinking about.


I had the fortune to meet Craig last weekend at NJMSP. I was a perfect late summer day for spectating - and racing I’ll bet. It was a blast watching Craig chase a pack of bigger bikes, nipping at there heals. I suspect it’s quite unsettling being chased by a little 200cc machine. Craig added a little drama on Saturdays second race, stalling at the start. A clever technique to put the bigger bikes at ease and lower there guard.

I also want to thank Craig for letting me poke around his bike, and ask questions. I think he gave me what I will take as the best advice so far - “Run the stock cylinders for the first season while you get the bike sorted and settled. And look for a 2nd set of cylinders to port”. So that’s the updated plan.

I’ll have lots more questions coming up, but for the moment let see some pics.


Starting to test fit the fairing and tank


Looks like I may need to cut, and reattach the head brace

It was installed by the previous owner and is 45* to the head, not parallel to the ground.

I’ll also need to do a little bit of modification to the faring to accommodate the bigger carbs

Craig needed to do this as well, and I would have likely missed it if not for seeing his bike this weekend.

And a view of the cockpit
Al Pritchard
Highlands, NJ

BS175 Racer

Offline craig641

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Re: Racer Resurrection
« Reply #52 on: September 24, 2015, 08:53:27 AM »
Al - just something to think about.  In your sideview picture it shows that your ass is going to be placed almost directly over your rear axle.  That's going to put an awful lot of weight to the rear of the bike, that's going to affect your handling.  Probably not a lot you can do about it if you're going to use that long tank.  Also if you keep your seat in that spot and your footpegs where they are located that's going to put your feet forward of your hips by a lot when you're sitting on the bike.  That won't be comfortable for your riding.

Craig

Offline al_pritchard

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Re: Racer Resurrection
« Reply #53 on: October 06, 2015, 08:32:59 AM »
I’m afraid your right Craig, but I may not be able to completely correct the situation. I think the wife will kill me if I go buy a different tank at this point. It looks like the flange of the top and bottom molded parts are joined with a substantialy thick lip that extends almost two inches past the internal space of the tank on the top. If you look closely at the tank you can see the lip. I’m going to have a good look inside the tank today and get on the phone with airtech to see if some of that can be trimed off. If it can I think it will go a long way to moving the tank and me further forward. If not… new tank or longer swing arm sometime down the road.

I’m not to worried about the body position in regard to foot and hip placement. It doesn’t feel to bad sitting on it. Although 5 minutes in flip flops standing still is a lot different than full race gear and time.

Shameless Selfe


On another note. I’m starting the process of adapting my new triple clamp and forks. I’m wondering if any of you remember the bearings sizes or part number you ordered. Paul mentioned he had to skim the stem to make it work for him. But I think he may have a different triple clamp.

The races I pulled out of the Bridgestone neck are 47.60mm / 1.874in wide. And the stem on my new clamps is 26mm. The challenge, aside from finding a bearing with the correct outer diameter and bore diameter. Will be fitting the bearing in the upper neck cup. As it is only 5.5mm deep, I’m assuming that the bearing race will extend above the neck.

Bridgestone triple clamp on the right


Neck Measurements


Did anyone get different measurements? I'm using a rather cheep digital caliper so I suspect it may be off.
« Last Edit: October 09, 2015, 08:46:21 AM by al_pritchard »
Al Pritchard
Highlands, NJ

BS175 Racer

Offline al_pritchard

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Re: Racer Resurrection
« Reply #54 on: October 26, 2015, 02:31:49 PM »
Ordered the bearings from Allballs to attempt the conversion to taper bearings. So far, so good.

NOTE: I’m not using the Bridgestone steering yoke, so keep that in mind as you follow along.

99-3509-5 (25mm x 48mm x 13mm) for the top bearing. I selected the 13mm tall bearing for the top. Because I was a bit worried about having the bearing and race extend so far above the top of the neck.

99-3505-5 (25mm x 48mm x 15mm) for the bottom. The recess in the bottom of the neck is much deeper than the top and I wanted to make sure the bearing was tall enough.

Both races fit nice and snug into the neck. Put’s my ability to use calipers at questions based on the last posting.

Next up will be skimming the neck on the new yoke.

Steering stem dimensions:
Top of the stem, with threads: 25.32mm (0.997in)
Body of the stem: 25.92mm (1.020in)
Internal diameter of the stem: 18.55mm (0.730in)

I’ll need to remove a little.
Top of the stem, with threads: 0.36mm (0.015in)
Body of the stem: 0.96mm (0.038in)

Top Race




Bottom Race




Fork Yoke
Al Pritchard
Highlands, NJ

BS175 Racer

Offline al_pritchard

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Re: Racer Resurrection
« Reply #55 on: November 02, 2015, 11:01:48 AM »
A little more progress over the weekend.

With the bearings fit, we skimmed down the steering shaft just a bit to get it to fit the 25mm bearing. Didn’t need to take a lot off. The threads are a bit more square, but plenty of thread still left to hold. (Click image below for video)


The entire set up fees much more solid than the original roller bearings. Both smoother to turn, and more solid feeling. I was able to use the bearing dust cap from the Bridgestone for the top. I’ll need to look around for a solution for the bottom bearing. And I’ll need to remove the old steering stop at the bottom of the neck.






Next steps will be to address the Bridgestone front hub, and the Ceriani axle. Speaking of the axle, does it look like it’s sticking out a little far? I’m wondering is its not the correct axle.
[url=https://flic.kr/p/ABUUa6]


I also did some trimming on the tank to see if I could get it a little further forward. Craig mentioned earlier about my body position in relation to the rear hub. I managed to get the tank about an inch forward. Every little bit helps. Brackets for the tank and faring are all ready. Just need some time with the welder.
Al Pritchard
Highlands, NJ

BS175 Racer

Offline rwgibbon

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Re: Racer Resurrection
« Reply #56 on: November 02, 2015, 05:18:20 PM »
Al,

I give you a lot of credit. You have skills well beyond what I have.

It is great to see what a real mechanic is able to do.

Thank you for posting your progress.

Randy

Offline slawsonb

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Re: Racer Resurrection
« Reply #57 on: November 02, 2015, 05:38:49 PM »
i agree, Randy. Pretty awesome.
...bert

Offline al_pritchard

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Re: Racer Resurrection
« Reply #58 on: November 09, 2015, 08:56:16 AM »
Don't oversell me here guys. I'm just hacking my way through this.

The real mechanic is a busy of mine who "guides" me to the better solution. He did a lot of work on snow machines back in the day, so he got a little 2 stroke knowledge.  ;D
Al Pritchard
Highlands, NJ

BS175 Racer

Offline slawsonb

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Re: Racer Resurrection
« Reply #59 on: November 09, 2015, 11:05:38 AM »
Modesty appreciated. I'm sure many of us have been fortunate enough to have a mentor who helped with and taught skills. I, for one, am enjoying watching this. Nice project Al. Don't sell yourself short.
...bert

 


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