E: Engine Liner/muff clearance

[Cyborg]

A little heads up regarding plate glass for flattening components. I was loaned a piece of thick plate glass big enough to take a twin crankcase half. Check the glass in several directions with a good straight edge first. (I didn't.) It was not quite flat!
Because the casting is so large you end up with a dip or a high point in the middle depending on which way up you have the piece of glass. If it is too bad you will struggle to get a good joint when you put the halves together. The cases on my "B" cases are so thick and stiff the through bolts struggle to close any gap. I have had a leak that has annoyed me all last year so it is coming to bits any day now for a rebore and I will look to see then if I can find a good jointing compound to seal the gap. I dont want to remove any more material from the crankcase joint faces if I can help it as the end float on the crank assemble will be too small.
What fun we have working with old bits.

I checked it against two cast iron parallel straight edges only to find that the glass is almost straighter than my two parallels. Put the two parallels together and can see daylight in between. I can now use them for door stops or yard art.

 

[BigEd]

Eddy, If your cases are distorted, then a very light skim over them on a mill is the best way. But the main issue to contend with is the cylinder spigot holes close up slightly. The crank and gearbox internals will accommodate some slight changes in overall width. Modern silicon sealants will fill gaps in cases, although it is hard to stop assembly oil from sitting on the joints where you need the sealant to go off without this "Lubricant" getting in the way. I always use "Threebond" sealants and these products give excellent results. Cheers for now...................Greg.

Dear Greg,
Thanks for your reply, good information as usual.
The cylinder spigot holes is something I will I will have to check if I am able to remove mmore material. At this stage I hope not to have to remove any more material. If it comes to that I have a friend with a bridgeport mill who can do some skimming.
I used threebond and excellent though it is it didn't manage to do a complete seal. I can see that I will have to investigate further with some dry test assemblies.
Bruce: I have used silicone on some poor joint faces before with good success but I am conscious of problems that may occur if silicone ends up in the wrong place and gets into the oilways. Not too much of a problem for a chaincase cover but a possible problem for crankcase or timing cover. This may well be the way to go but I also have one or two ideas I may try as well.
I have finished fitting dro's to my lathe so that can now go back against the wall to create space to get the ike up on the bench and start the stripdown.
Another job will be to source a large and truly flat surface plate.

 

[greg brillus]

Thanks Eddy........I am interested to know what might have caused the distortion in your cases.......Perhaps from a previous weld repair job. The job of cleaning up the faces and even re- boring the cylinder spigot holes is actually not too bad a job, but it does require the removal of the hold down studs, which can go either way when luck is concerned. It is reasonably common for the right rear studs on either cylinder to slightly clash with the inner face of the inlet cam follower spindles. I guess at this early point, it may pay to find where the high/low spots are first and take it from there. Cheers for now................Greg.

 

[bmetcalf]

Kitchen granite countertops are popular here and the sink cutouts can be crankcase sized and quite cheap from the installation companies. I got an 18" x 18" free. Maybe available in your area.

 

[Chris Launders]

I saw a video the other day of piston aero engine building, on the crankcase joint they used a sealer with a silk thread laid along the face, it seems to me this may work especially if the thread is soaked in the sealer where the gap is widest, or multiple strands in that area.

 

[Phil Davies]

Eddy,
With regard to a sealer to seal your crankcases, what you need is the sealer used by the racing two stroke brigade, Suzuki produced 'Suzukiseal' for their RG500s and its what I used on all my TZ750s with great sucess. There may be a more modern equivilant.
The sealer was produced because once the original cases were parted for the first time, they distorted all over the place rendering them impossible to seal properly at the crankcase and this stuff was the only effective solution, apparently RG cases distorted more than TZ cases (and the TZ's were bad!).
Back in the day it was not cheap then, but it certainly stuck to surfaces and filled some very large gaps.

 

[BigEd]

Eddy,
With regard to a sealer to seal your crankcases, what you need is the sealer used by the racing two stroke brigade, Suzuki produced 'Suzukiseal' for their RG500s and its what I used on all my TZ750s with great sucess. There may be a more modern equivilant.
The sealer was produced because once the original cases were parted for the first time, they distorted all over the place rendering them impossible to seal properly at the crankcase and this stuff was the only effective solution, apparently RG cases distorted more than TZ cases (and the TZ's were bad!).
Back in the day it was not cheap then, but it certainly stuck to surfaces and filled some very large gaps.

Just done a quick search for Suzukiseal but didn't find anything. If someone does know a bit more about this sealant or where it might be available please let me know.

 

[Phil Davies]

Eddy,
I'll ask around the two stroke racing crew and PM you directly

 

[vibrac]

Post #11 in https://www.vincentownersclub.co.uk/index.php?threads/to-peterg.5312/#post-35873 has a suggestion. I searched for "silicone" by "riptragle1953" on the Forum and found, surprise, surprise, a number of opinions.

the forum has been going long enough now that often a search is more profitable than a question the other day I read a post and thought" well I dont agree with that!" then I looked to the left and it was one of mine from over four years ago!

 

[Cyborg]

Eddy,
With regard to a sealer to seal your crankcases, what you need is the sealer used by the racing two stroke brigade, Suzuki produced 'Suzukiseal' for their RG500s and its what I used on all my TZ750s with great sucess. There may be a more modern equivilant.
The sealer was produced because once the original cases were parted for the first time, they distorted all over the place rendering them impossible to seal properly at the crankcase and this stuff was the only effective solution, apparently RG cases distorted more than TZ cases (and the TZ's were bad!).
Back in the day it was not cheap then, but it certainly stuck to surfaces and filled some very large gaps.

Perhaps it was the same as Yamabond or Hondabond and you are looking for Suzukibond. The Honda and Yamaha versions are from 3 Bond and I assume the Suzuki one is as well. Different types of 3Bond available. It has a shelf life and best kept in the fridge next to the Lea and Perrins.