Bridgestone Motorcycle Parts Discussion Board
Bridgestone Tech Talk => Engine => Topic started by: stingray68 on May 09, 2016, 09:50:31 AM
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I have finally freed the piston from the cylinder and removed the cylinder from the crankcase. Unfortunately the engine is still locked up. My question now is what to do from here. I am looking for advice as to what to do next. When I take the bike out of gear the drive sprocket spins freely, but when it is in gear it does not move nor does the kick start move the piston. Anyhow, thank you to everyone for your help and encouragement....Mike
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Mike,
Sounds like it needs a complete rebuild. The transmission may have rusted if it was sitting without oil for a long period. The kickstart mechanism may be broken/jammed? Bearings could be shot? Endless possibilities? Good luck! Steve
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That's kind of what I am afraid of. I drained the crankcase after I bought it and the oil looked good, but that's not to say they did not add oil an hour before I came to look at it too. I would consider myself a novice at best and am a little leary of taking on a full rebuild. Can anyone recommend a good mechanic? I did find a guy to work on it locally for $40/Hr, but I have no idea how long it would take to this job. I have downloaded the maunals off this site so I think with time and patience I think I could do the rebuild, but was really hoping to be riding not rebuilding this motor. Thank you all again for any information. Mike
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Mike, just start plugging away and ask alot of questions. Anyone you find to work on your bike will probably have less direct experience than you. I don't think you can go too far wrong. At least get it stripped so you can determine if its the trans or crank that is locked. Second the good luck!
...bert
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Okay, maybe I'll give this a shot. Does anyone know of any special tools that I will need to tackle this job. I have already been through the parts book and made a list of bearings, gaskets, o-rings etc that I might need? Thank you all again for reading and sharing your thoughts and ideas. I am sure that I will be posting some more questions as I get into this. :) Mike
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Look on pages 56 and 57 of the 90-100 Parts Manual here:
http://bridgestonemotorcycleparts.com/index.php?action=downloads;sa=view;down=82
These pages show Service and Special Tools. I am not a 90 guy, so hopefully one of our 90 whisperers will chime in, but my guess is that the puller and sprocket stopper are the important ones for an engine overhaul. I'm sure some of the members will have some tips on this.
...bert
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You're right on the important tools. The flywheel puller can be a normal steering wheel puller from your auto parts store; you may need to get different bolts than those that come with it and you may need to grind the slots closer to the center to align with the flywheel holes. The sprocket stopper is handy, but I've used a large pair of water pump pliers or vice grips. Just be careful to not bend a tip of a sprocket tooth if the sprocket is well-worn.
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Please keep the info coming!! I have been going through the parts manual gathering o-rings, gaskets, oil seals, bearings etc that I think I will need to do a complete rebuild on this engine. Does anyone already have a list compiled of the recommended parts to be replaced? If so can you please share it with me. I would like to go ahead and do the whole job at once without waiting for parts every other day. Thank you all again.....Mike
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Hello All! I got around to taking the RH side of the crankcase apart on my 65 Sport 90. I have attached some pics for you all to look at and see what you think so far. I appreciate all comments and advice, so please keep it coming. Thank you all in advance, Mike
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More Pics
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Few More
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Hey Mike,
Are you sure you have a 90 "Sport"? It looks like the cylinder is cast iron. The 90 Sports use an aluminum chrome lined cylinder. The piston, rings and carb are different as well. Good luck, Steve
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Well, I think so....I'll post a picture of the bike before I tore it apart. It does look like a sport, the title says sport (doesn't mean much) and the rear tire has the dual sprocket. As it sits right now the crankshaft does not turn and likewise the kick start is also locked up. Thank you all for looking, Mike
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Mike,
The 90 Sport has a single 34 tooth rear sprocket, 17mm carb and aluminum cylinder. It sounds like you have a Trail or Mountain. There should be a tag with the serial number and model. It's located on the right side of the frame below the air filter cover/side cover. A picture of your bike would help. Good luck, Steve
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The tag says BS90-T. Would I be correct to assume this means a trail model? That being said, should I continue with the dis-assembly of motor and crankcase? So far I think everything looks nice. What do you all recommend for the cylinder and piston/rings? Thanks for all the info....Mike
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Mike,
Yes, it's a Trail. The cast iron cylinder is easier to work with. There are two oversized pistons available and you won't need to get the cylinder re chromed. Go for it! These are cool little bikes, Steve
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Hey Steve,
Thanks for getting me straight on the model number. (I should know better then to believe what the title says.) Don't suppose you know off hand the oversized piston and rings that I would need? Also, I mentioned this before about the special tools. Does anyone know if these are available for sale? Thank you all...Mike
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Mike,
You'll need to have the cylinder bored and honed to match the piston at a machine shop. They can measure the bore to determine which piston/rings to use. There are two available .25/.50 over stock. You can find the part numbers in the parts manual. If you haven't downloaded it here's a link http://bridgestonemotorcycleparts.com/index.php?action=downloads;sa=view;down=82 Hope this helps and good luck, Steve
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I am making some progress with the engine dis assembly and have yet another question and it may be dumb, but....In the repair manual it says after you remove the clutch assembly you should have the transmission in 1st gear. I have never been able to ride this bike or any other Bridgestone for that matter, but what is the shift pattern for the BS90 Trail? Thank you to everyone that has chimed in to help me out so far!! Mike
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Look on page 32 of the service manual. The pattern is 4 down, but it recycles through Neutral between 4th and 1st. so it may be hard to tell where you are since it will never stop shifting in either direction (gotta watch that the first time you ride it...;-). The bertogram below may help.
...bert
For front shift pedal:
|-N->1->2->3->4->|
|-----------<--------|
Also works in reverse for back shift pedal... ;D
Hey 90 whisperers, chime in if I got this wrong...
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Thank you Bert for the info! Another for you pros out there.....The repair manuals suggest using special tools (piston seat, clutch wrench, etc..) for assisting in the dis assembly and re assembly of the engine and crankcase. I guess what I would like to know is should I try to purchase these tools prior to going any furthur with the dis assembly? Or is it possible to do the work without these tools. Also, please keep in mind I do not have access to a machine shop or welder to make my own tools or fixtures. Thank you all for your help....Mike
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Mike,
You can do without the special tools. Use a small piece of wood or aluminum for the piston seat. It stops the crank from spinning while tightening/loosen nuts. The sprocket stopper does the same job for the transmission. You can hold the sprocket with the chain. The left hand thread special nut on the right side of the crankshaft can be removed without the tool. It takes some ingenuity. I used two slotted screwdrivers and a pair of pliers. Good luck! Steve
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On the subject of special tools, I'd agree that none of them are really necessary for stripping the 90/100 engine. For the left-hand thread crank nut, you only need a special tool (peg spanner) for the early model 90s which had a special nut. Letr model 90s changed this to a normal hexagon nut (still l.h. thread though), so chances are yours can be removed with a normal socket or ring spanner.
As for the locked motor, the fact that the sprocket spins freely when in neutral ( and that you can select neutral) means that you probably don't have a rusted/seized transmission. I would suspect maybe something has broken in the primary drive and jammed that - or possibly you've got a broken disc valve and bits have jammed that up preventing the crank from turning. he good news is that both can be checked without delving too far into the innards - just removed the clutch/primary drive casing and all will be revealed.
Graham
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Good Morning All, Graham, thank you for the input! I suspect you are right about something being broken. I was looking over the motor and I pulled a small metal fragment out of the area where the connecting rod goes into the crankcase.....So something is snarfed up in there. I think like you said once that primary casing is removed I will be able to see what the root of the problem is. I will post a few pics once I remove it. Thank you again to everyone for the help and wisdom in with these machines...Mike
P.S. Thank you all to all of our veterans out there on this Memorial Day weekend and everyday for that matter!!
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Amen on the thanks to veterans!
...bert
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Hey Guys,
Well, I am getting to spend a little time this weekend and am wondering what is the easiest/best way to remove the pinion gear from the crankshaft as seen in the pictures. The manual refers to a special tool I believe. What do you all recommend. Thank you! Mike
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On a 350 the large driven gear that runs on the counter (clutch center) shaft is held with a special tool while the nut is removed. I'm sure there is something equivalent here.
...bert
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I just want to clarify that I am trying to remove the rotary valve plate so the pinion gear needs to be removed. Thank you all again....Mike
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Sorry, if I misinterpreted. If you have the primary nut removed (which it appears you do in looking more closely at the pic), then you just need a puller to remove the pinion. You should be able to find a suitable one at your local auto parts store or Amazon/ebay. Should pull right off , but may require a tap with a punch in the center of the shaft when you have the puller tightened.
...bert
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You hit the nail on the head.....that is what I needed to know. I just wanted to be sure there were no special tricks to removing the pinion before I get to far into the process. Thank you again for all your help.....Mike
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Hi, Mike,
It seems you have the early type of pinion nut on your engine. The special tool is simply a tube with a bar welded to it and the business end cut away to leave 4 small tags which fit into the slots in the nut. You may get away with using a soft drift to tap the nut round (but use an aluminium or brass drift to avoid bruising the nut).
Honda used a similar type of nut to secure their centrifugal oil filters to the end of the crank. The common dodge there was to find a conventional socket that just fits over the nut, and then shape a short length of welding rod into a "U" shape to fit into tow opposite slots in the nut. Then tap the socket on over the nut and welding rod and that usually gave enough purchase to loosen the fastener.
Whatever you do, remember that the nut is a LEFT HAND thread!
Once the nut is removed, the pinion should just slide off the crank splines. No puller is necessary. If it's a bit stiff, try using a tyre lever under the edge of the pinion to persuade it to start moving.
Good luck.
Graham
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As usual, I learned something from Mr. Weeks. I did not recognize the nut as a nut... ;D Sorry if I misdirected (again).
...bert
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Hello Everyone!! Well, I was able to remove the pinion and rotary valve plate and it looks pretty crunchy in there. I will continue the disassembly. If anyone has any comments, concerns, advice....Please let me know. Thank you all....Mike
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Hey Mike,
Looks a little rusty. Was the disc valve in there? Does the transmission/crank spin freely now or is it still stuck? Good luck, Steve
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Hey Steve,
The valve was there and I have included two pics of it attached. Also, the transmission and kick start all spin real nice. The crank has a little movement now, but not much. I have two tasks ahead of me at the moment. 1) Remove the circlip from the kick start shaft. What is the best way to do this? 2) I need to remove the piston from the connecting rod. What do you recommend for that? From there I think I can separate the two sides of the gearbox and see what's keeping this from moving.....Thanks for the quick response!! Mike
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Mike,
There are pliers made for removing circlips/snap rings. They're not expensive available at any auto parts store. http://m.ebay.com/itm/New-4-in-1-Snap-Ring-Pliers-Plier-Set-Circlip-Combination-Retaining-Clip-0-SHIP-/171493822195?nav=SEARCH
There is a small spring clip that holds the piston pin in place. Regular needle nose pliers can be used to remove them. It looks like the crank bearings are rusted and causing the problem. Could be the rod (big end) bearing too. Looks like a complete rebuild is needed bearings, seals/o-rings and gaskets. Hopefully you can reuse the transmission bearings. Good luck hope you get it back together and running, Steve
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Well, so far so good! I am ready to separate the two halves of the crankcase, but the gasket and sealant are still doing a great job after all these years. Anyhow, I would like to know if anyone has any good advice on separating the crankcase, but still keep control of it and not having pieces come crashing to the floor. I was thinking about putting the heat gun to it to help soften up the sealant. Any advice is welcomed and appreciated. Thank you all....Mike
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The key will be to have it in the right orientation so that the fewest things come loose upon separation. I expect you want it laying flat on one side or the other. You may be able to tell how to orient from the parts manual, but wisdom from our 90 members would be best!
...bert
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That would sure be something if all 90 members replied! :P
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Go slow. Use a rubber mallet to tap around the seal. It will take some time. Concentrate on the area near the dowel pins. There is one in front and one in rear of the crankcase. Use the parts manual to locate the pins. Go slow! DON'T use a chisel or screwdriver to wedge them apart. That will damage the cases. Best to have the right side (clutch) down or the guts may fall out. Have you read the service manual? It will answer some of these questions.
http://bridgestonemotorcycleparts.com/index.php?action=downloads;sa=view;down=18
Take your time. Don't smash it while tapping, a little heat may help. Remember it's aluminum and can be damaged easily. Good luck take your time, Steve
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Thank you very much for the info! I would have to say that one of the biggest lessons I have learned since starting this project is to have patience! I have been reading the manual along the way and am glad to say that even I can follow along. It is great to have you guys for the experience of actually having done this before. I will take it slow and keep you all posted on my progress. Thank you again, Mike
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I used a plastic putty knife and tapped it lightly and slowly between the halves to get things moving. As stated previously here - go slow and take your time. Once the main bearings (crank bearings) start to move out of the case halves, it will come apart pretty quickly. Looking at the rusty side you have in the picture, it more than likely that this side will be a little slow to drop out.
I would suggest you have that side down as the transmission is less likely to come apart if you take the left side off of the right side. Here is a picture of a 50 sport motor which is pretty much the same configuration as your 90.
Dan
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FYI,
I just got an Armstrong 2 1/4" Face Spanner from eBay. It's the perfect tool for the "sprocket stopper". It fits the 14 tooth front sprocket on BS90's. The handle is long enough to rest on the crankshaft while torquing the nuts. Here's a link to the tool. There's a large price range. I only paid $5. Just an option, Steve
http://m.ebay.com/itm/Armstrong-2-1-4-in-Face-Spanner-Wrench-Heat-Treated-for-Greater-Strength-/321975659322?hash=item4af73eab3a%3Ag%3A3pwAAOSwFqJWlwMB&_trkparms=pageci%253A980bd468-3014-11e6-8a13-74dbd180b8af%257Cparentrq%253A4130dbc11550a6a8cb43dd6afffef29d%257Ciid%253A1
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Awesome....Thanks Steve. If I don't find one at a better price I'll pick that up. Check out the pics below. I was able to get the gearbox split and what a rusty mess the crankshaft is. Piston skirt is broken. Not sure what this guy did to this bike, but wow!! Anyhow, what do you all think about this situation. Should the crankshaft pull easily through the gearbox half? This one seems to be stuck. Probably rusted. What do you think? Do I replace the crank halves? Bead blast these? As usual thank you for your input....Mike
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Mike,
It looks like it may take a shop press to remove the crankshaft from case. The crank halves might be usable. The rust can be removed. Try "Metal Rescue" or "Evaporust" they remove rust without damaging the base metal. You will need new main crank and conrod bearings! You could probably find a used crank on eBay. Good luck, Steve
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Hello Everyone,
Well sadly the Bridgestone engine rebuild has taken the back burner to other projects, but I am looking to continue shortly. My next issue is removing the crankshaft and bearing from the housing. Right now the bearing is rusted to the right side of the housing. Does anyone have any good suggestions on how to remove the bearing and crankshaft? My arbor press is not deep enough and I do not want to damage the crankshaft. As usual....Any and all help is greatly appreciated. Thank you, Mike
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Not exactly sure what you are describing, but if the bearing is rusted between the outer surface of the bearing and the aluminum housing (essentially expanding to wedge the bearing in the opening in the housing), then soaking it in some penetrating oil might loosen it enough to allow it to be extracted.
...bert
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God that looks awful. I've got a 90 engine I don't need, would let it go cheap if you want it.
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Right on! Members helping members! I love it! Nice going grundlegrabber!
...bert
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I honestly don't know what I would have done without the help of the members of this site. Thanks to all you guys!....Mike
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Its all about keeping the old bikes going. Every one that gets fixed up is one less that was lost to the ages. Sharing knowledge & parts among members is so important to the survival of the species. So many times I would have been stuck without the help of others. Always try to pay it forward when I can.