Bridgestone Motorcycle Parts Discussion Board
Bridgestone Tech Talk => SR Racer Talk => Topic started by: Mike Anderson on November 16, 2014, 09:56:04 AM
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Dropped off the engine from my unrestored racer to Steve Reed last weekend. We were on a little trip visiting friends and family and had an opportunity to go by Steve's for a day. I am not familiar with the small engines and Steve offered to help. We will show some future photos of the engine coming apart and going together. It will not be a show bike assembly as the rest of the bike is not going to be restored. I want all the parts to go back as they were. Steve will be basically cleaning the metals and replacing seals etc. as needed. I am just cleaning the bike up, replacing the cables and getting it ready for engine reinstall. The little bike still has it's original tires and other pieces, I had the seat recovered and the number panel repainted otherwise unrestored. All chrome is pretty good so just cleaning. Hope to have it running by spring. Stay tuned for photos as we get them.
Later Mike
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Mike,
I managed to free the piston that was sized in the cylinder and then set about to get the crankshaft to turn etc.
Pictures of the cylinder and piston so far this engine is in great shape for how old it is i will pull the crankcases
This coming week.
Thanks.
Steve.
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More pictures,
Note the piston only had one ring in.
Thanks.
Steve.
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More pictures.
Thanks.
Steve.
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One more picture.
Thanks.
Steve.
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Hi Steve,
Looks like progress is being made. Between the two of us the little bike should be ready to ride in the spring. I will get busy cleaning up the bike on my end.
Later Mike
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Mike,
When you get the engine back how about a video!!
Thanks.
Steve.
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Sounds good Steve, I can make a short video of engine going back in bike and then one of it running. Have been waiting for a long time to hear one of these run. Just sent parts list to Richard for the engine and talked to him about them. Should have them later this week.
Thanks Mike
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I went through a GP 100 engine this past year and just from these photos I can see many differences between the two engines. These pictures are great! Looking forward to seeing more as the project continues. Good work Steve.
Roland
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Hey Roland. Just as a learning point for me (and maybe others) could you share your observations? thanks
...bert
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I just rebuilt my 100 Sport engine and am also curious the differences between it, the GP100 and the SR100.
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As far as the differences between my 100 GP engine and the Racer go, they prompt more in the way of questions than answers. The first thing I noticed was the wiring coming from the Left crankcase cover. The bike doesn't have any need for a lighting coil in the magneto but it appears to only have a few wires coming out of that area compared to six or so I have. My bike is 6V and I believe these ran a 12V total loss ignition system so I'm not sure if it even has a rectifier or what (?) size coil. They are listed as having a key switch and without a charging system they wouldn't need much in the way of wiring for an on/off key switch.
The clutch basket on the Racer looks deeper and if my counting is correct they might be running an additional set of plates. I know they have a different Right side crankcase cover than a stock 100 so maybe it's deeper to accommodate the clutch and larger carburetor. The stock bike runs a 17/18mm carb and the racer runs a 22mm. The spigot on the rotary valve cover is different than my bike, perhaps to accommodate the different (larger) size carb. They also ran a different rotary valve. Cover reminds me more of a cover off a 90 or 175.
Not sure why they list a different piston and only use one ring. I thought I recall these having a higher compression ratio than stock. Would this improve lower end lubrication if you're running premix?
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Thanks Roland. The single ring would probably improve ring/cylinder lubrication since it's getting blasted from both sides and no dead space (in between 2 rings) to trap carbon or other crud.
...bert
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Bridgestone SR-100 engine,
when i get more into the engine i will be measuring all the parts and i will list all the sizes so you can see differences between the
GP 100 Bridgestone engine and the SR engine.
Thanks.
Steve.
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Steve,
Should be interesting to see the difference in port heights, rotary valve timing and possible piston differences between the stock 100cc engines and the racer. Keep us in the loop.
Thanks Mike
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SR 100 ENGINE,
Well i got crankcases pulled apart and this is what i have found out so far.
The right side crankcase is damage where the stopper ratchet arm fit into hole
Stripped teeth on the kick gear, one bent kick start shaft we will need new
Crankshaft seals plus main bearings the crankshaft will need to be set-up.
List of parts so far.
Ratchet arm.
Stopper.
Kick -shaft.
Kick gear.
Ratchet spring and return spring etc.
Shift pin holder.
Gear change shaft.
Plus crankcase gasket.
Thanks.
Steve.
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One stripped gear etc.
Thanks.
Steve.
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Kickstart parts.
Thanks.
Steve
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Crankcases split.
Thanks.
Steve.
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The rest of the parts to be cleaned etc.
Thanks.
Steve.
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Great job Steve,
I will get all the parts lined up an hopefully the little motor will be good as new when you work your magic. It is great to have you familiar with the small motors, I have only worked on 350's. During the holidays I hope to be able to spend a little time cleaning on the bike itself. Would be a shame if you get the engine finished before I get the bike cleaned up.
Thanks Mike
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Great pictures Steve. Looks like the clutch pack has 6 friction plates and 5 inner plates, which is one more set than stock 90/100's.
Is that red fitting on the rotary cover spigot an adapter for the larger carburetor?
Roland
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Starting clean up and repair on SR-100 chassis today. First thing on list is to straighten the handle bars. Looks like they were bent in a right side crash. Hopefully I can get them to come straight, don't have any crease in them so should work. Also want to try cleaning paint or whatever from decal which was applied at sometime in it's history. Not sure what it says but looks like racer something. Hopefully I can save it, parts of history are nice to preserve. Will post more pictures as it goes. Ignore the date on pictures, need to adjust camera's date.
Later Mike
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Roland,
The fitting is for a larger carb, like i said before this is a very interesting engine to work on!
Thanks.
Steve.
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Steve, it looks like the red fitting is the plastic insert from inside the end of the 22mm carb.
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Hi Karl,
I think you are probably right. Don't remember if there was an insert still in the carb after it came off. Hopefully Steve can get the little engine back up and running, probably going to need another case if this one cannot be welded up. Was hoping to use all the original external parts, trying to keep the bike original looking. New stuff gives it the restored look since everything else would need cleaning to match. Hope everyone has a great Thanksgiving holiday.
Later Mike
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Was hoping to use all the original external parts, trying to keep the bike original looking. New stuff gives it the restored look since everything else would need cleaning to match.
Later Mike
If you or he can find a good used one, it may have the necessary patina.
Heating a new one with a torch should oxidize the surface enough to get rid of the shine, but there are probably other ways to make it even better (worse looking).
Nice project.
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Thanks Karl,
Hopefully we can find a case to use, new or used. I think they are different than the standard case, so may be tough to locate. I don't have it in front of me but am assuming there is no mount for oil pump and the intake port is different. Probably can file and contour the port to work but no nothing about the oil pump mount surface. Maybe it can be blocked with a thin plate. Anybody have any experience with these engines. I have not, never worked on any of the small ones only 350's. Hope everyone had a nice holiday.
Later Mike
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I'd guess they used the same casting, so the intake port would have been the same as stock to start with, just hand worked to open it up to match the rotary valve cover. They may have skipped the machining on the oil pump mounting, similar to skipping some of the machining on the SR175 case for the right side oil line, oil pump drive vent to the crankcase and the shift selector lever hole. However, if you put a cover plate on a stock case, it won't show once the carb cover is installed, so it will look OK from the outside.
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A work of art. Hand ported intake and transfers in these 100 SR cases. Rest of the casting is basically the same. Oil injection ports may not be machined but a standard case will still work as they are not needed. Outer case is where everything changes. SR100 has sand cast one off individually produced right side case, carb cover and carb cap. Engine cylinder is also sand cast as is the rotary valve cover and front brake plate. Crankshafts are factory processed, special piston and rotary valve. Special carb, choke delete. SR's also have heavier clutch and rotary shift stop. Frames are special, there's a lot of subtle differences also. Love these bikes. Nice work so far Steve. I'll call you about your case and front fender Mike. Thanks, Mark.
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Morning Mark,
Thanks for helping with the SR100 into. Let me know what you find on the fender.
Later Mike
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Crankcase,
Removed the bearings and the bushing and the studs from the damage casing.
All cleaned up ready to send back to Mike to be repaired.
Thanks.
Steve.
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Crankcase,
Picture of the other side of crankcase.
Thanks.
Steve.
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Can't wait to see what I can do with it Steve.
Thanks Mike
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Mike,
Picture of your old kick-start shaft next to the new one, note no cir clip grove on the shaft.
Thanks.
Steve.
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Hard to figure. Obviously a change was made to correct a problem. Gear and other parts surely needed to be located in a position. Mark if you are reading this, do you have any ideas? Let us know.
Thanks Mike
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SR-100 Bridgestone,
I put the clutch cover in the tank with a new mix turned out nice.
Mike told me not to over board with the cleaning but i can not
Help myself ;D
Thanks.
Steve.
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SR-100 Bridgestone,
On the inside of the clutch cover you can see some damage!!
Thanks.
Steve.
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SR-100 Bridgestone,
One more picture of the inside of the clutch cover etc.
Thanks.
Steve.
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Great job Steve, can't wait to get the little engine running. I will work on the case immediately.
Thanks Mike
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Yeh I'm scratchin' the old noggin a bit over the missing cir-clip. Not that the groove and clip are missing, but why. I have a shaft just like the one you pulled out. I know of only one place such a part could be acquired. This may be an SR only part and there does not seem to be a separate part number for it. The question is might the deletion of the cir-clip allow for replacement of the shaft without splitting the cases? Tricky proposition, I would think, as the internal components might be tuff to keep in line. When fully assembled, the missing clip would not allow the shaft to simply be pulled out so long as the return spring is still engaging the shaft. It could cause it to "walk" a bit though. I'm glad to see you are going to repair the center case. I do have one but repairing the one you have is the way to go and cheaper too. Front fender is a one and only 4410-5010 MS. That's a metallic silver painted fender. You will likely never find one. They were made of nonobtainium when new. A racer part designation from the 90-S 4410 series, it looks like The 90M, 90TR, and 100TR which are all 4411 series. Best replacement is 4411-5011 (XCI) or 4411-5600 (XCI). The 5011 is the exact dimensions. The 5600 is just a hair off. If I didn't tell you, you wouldn't know the difference. Both of these would look fine as is but they are chrome fenders and are pre punched with a few too many mounting holes for the SR so, to be 100% correct, you need to de-chrome, weld up a few holes and paint. I have an N.O.S. 4411-5600 if you need it. Mark.
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They were made of nonobtainium when new.
I had always suspected the existance of this element. Thanks for confirming my suspicion as it helps to explain many parts I have found unobtain - able.
ROTFLMAO...made my day!
...bert
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Yeh I'm scratchin' the old noggin a bit over the missing cir-clip. Not that the groove and clip are missing, but why.
The kick shaft with the cir-clip groove is used on premix 90 models part#2621-5002. The kick shaft that is plane (no cir-clip groove) used on oil injected models part#2621-3201. The crank cases have minor differences. I think the cir-clip keeps the kick shaft in place. A small modification to the crank case on oil injected models allowed for the cir-clip to be removed (I think?). Small flange (3mm) on crank cases of oil injected models replace cir-clip and locate kick shaft/gear. First pic premix 90 crank case B(right side). Second pic oil injected 90 crank case B.
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Nice work. The height diff definitely makes up for the clip deletion. As for the why, I guess they just flat out didn't need it. Mark.
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So I just had to do it. I pulled a spare 100 engine off the shelf and turned it on its side as level as I could get. I removed the return spring and pulled the shaft out. Everything stayed put. Cleaned the shaft off, a little grease and right back in again. I did it a second time and jiggled the motor a little bit with the shaft out. I had to slightly re-align the components with a screwdriver and the shaft went right back in. You just have to check that its clocked correctly so the return spring has proper tension. So it looks like if your careful, the deleted clip could save you some time if you needed to replace a damaged or stripped shaft. I tried it on a TMX motor and cannot remove the shaft. did they go back to using the clip again? Mark.
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As an engineer, I suspect the stress riser from circlip groove led to failures at that location and they figured out a way to remove it. They would have saved some money in the process, too, though and that could have been the reason.
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SR-100 BRIDGESTONE,
I cleaned the other crankcase and removed the crankshaft and the mains, plus the 2 gear shaft bearings.
So when i get the other crankcase back from Mike i can rebuild the motor and it will go back clean etc.
Thanks.
Steve.
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Picture of the other side etc.
Thanks.
Steve.
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Gearbox,
Picture of gearbox all cleaned up and ready for Assembly!!
Thanks.
Steve.
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Lookin pretty Steve. Can't wait to get the crankcase repaired and things together to run. Hopefully I can work on the chassis some this next week. Been kinda busy lately.
Thanks Mike
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The kick start shaft is bent and i also suspect the starter ratchet arm part number 2632-5000 is also damaged more parts!!
Thanks.
Steve.
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Carb slide,
The carb slide was stuck in the carb but ten minutes in the ultrasonic did the trick!!
Thanks.
Steve.
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Everything looks nice cleaned up. You can really see the difference in the aluminum castings between the smooth case and the sand cast carb cap next to it. Mark.
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Crankcases,
Got the crankcases back from Mike nicely ported, so i put them in the ultrasonic all cleaned ready to be rebuilt etc.
Thanks.
Steve.
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One more picture.
Thanks.
Steve.
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I just want to hear it. Please post a video when you get it running.
...bert
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There will definitely be a video. I have never heard one run even though we had a new one at the shop. We never started it. They are my favorite of the Bridgestone's mainly because of there small stature. Can't wait to hear the sound. Have heard the 350's with pipes many times while we were selling them and riding them. Will run an original set of chambers on my current 350 and also a set of Kataro's. Should be an interesting comparison.
Later Mike
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Bridgestone SR-100 Engine.
Picture of the SR engine coming together, sorry for the delay i had a very nasty virus on my computer.
Thanks.
Steve.
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Looking Good Steve!
One step closer to lift off Mike.
Lee
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Mike,
This is a better picture of your engine outside today.
We had snow yesterday and today we are in the 50s
Thanks.
Steve.
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Calm Down Mike!!
Very Nice Steve.
Lee
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Hi Lee,
The engine will probably make the unrestored bike look neglected. Steve does great work.
Thanks Mike
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No worries Mike, that Racer you have looks perfect in its current condition, elbow grease is all it requires.
Lee
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Thanks, I will do my best.
Later Mike
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Picture of the engine Mike,we will see you soon.
Thanks.
Steve.
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Looking good Steve, see you next weekend.
Thanks Mike
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Hey Mike,
You figure out how to include a sound track yet, looks like your real close to lift off now?
Take Care...Lee
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Back in the 1960's and 1970' the magazines often recommended using only 1 piston ring on a 2 stroke, to lower friction on the cylinder wall. I also race a SR
100 Racer back in 1969.