I have a complete gasket set that came with some parts I bought. They are made in India. The 2 base gaskets are each made of slightly different materials and measure .034 and .032 respectively. I may just make my own. What should they measure out at?
And the head gaskets are not flat, they have a raised ridge in the center and measure .028. The ones in the bike which I believe are originals are flat and measure .040 which I have read is correct. I like the idea of the thinner head gaskets unless there are some recommendations here that I shouldn't use them. I annealed them and plan to use Copper Coat on them. Then measure the gap between the head and piston with some solder. If it all seems okay, I thought I would shoot for the recommended under .040 quench or squish or whatever you want to call it by decking the heads keeping in mind the CCs.
Thoughts........Opinions.......Advice.......All welcome.
don't buy Indian parts, seriously. I've never gotten a part from India that was worth a shit
Okay. The only good thing is that I don't have anything in them. :thumbs:
You didn't mention which engine you're working with but assuming it's a RD350.
Base gaskets:
OEM Yamaha are .024-.025
Aftermarket replacement base gaskets are .019-.020 thick
Advice from Supertune posted on this forum a few years ago:
"So a .004-.005 difference in squish height, not a big deal on stock engine, but can make a difference in a hot-rod engine build."
Head gaskets:
Gaskets for a 350 are copper rings that are .040" thick. They are not interchangeable with the RD400 0.020" gasket
RD350_head_gasket.jpg
RD400_head_gasket.jpg
And as Mark just posted, don't use crappy gaskets. Not worth it!
Yes RD350. The thinner Indian base gaskets would lower the ports as well. Enough to notice???? I certainly don't know. But either way, they are going in the trash.
The Indian head gaskets that I have are like the top one in your pictures. They fit well enough, it's just that they are .012 or so thinner. They may be crap and won't seal. But I thought that I would check the piston to head clearance and the head CCs to make sure there are no surprises. If there is a problem, I think I can catch it soon enough and it is not a difficult job to switch out the head gaskets. I was seriously thinking about machining the cylinders for the 400 gaskets anyway as part of an attempt to gain the proper squish and compression gain. If the Indian head gaskets were to actually work, that would be a move in the right direction.
to be honest, you probably wont feel any difference . as far as the base gaskets go, you can cut your own out of good gasket material, ive done that plenty of times. the one thing you need to watch out for is to put both on and make sure they dont lay over each other at the top of the case. ive had to trim a bit off the sides (in) more times than not .
also make sure the heads arent warped.
as far as using the copper spray seal on the base gaskets.. i do that and have never had an issue. what matters the MOST is that they seal. just dont use any sealant on the base gaskets.
there will be no harm in bolting it together and then checking compression. Might be ok. :twocents:
Will do, thanks for the heads up. :thumbs:
The last few years, I rarely put any gasket on dry. Hylomar has become my go-to sealer on gaskets that would otherwise go on dry. Great stuff that doesn't 'dry' so it allows for disassembly without major hassles. Permatex has a version that is stocked by most parts stores and is much less expensive. Just an additional level of 'insurance'. www.permatex.com/products/gasketing/gasket-sealants/permatex-permashield-fuel-resistant-gasket-dressing-flange-sealant-2-oz
TBH i usually will use anerobic sealant, or grease on the base gaskets. they really see no pressure. 0.02
On my '75 350, I went the route of decking the tops of the cylinders flat for 400 head gaskets. This brought the squish down from 2.1mm to 1.6mm, as the 400 head gaskets are .020" vs 0.40". Still more squish than most recommend, but it's a starting point. I left the heads alone for now.
I'll go ahead and admit I did the "machining" myself with a file, and then sanded on a surface plate. :cheers:
As I said, going to the 400 head gasket was my plan in the beginning. The biggest challenge for me personally in going with the 400 gaskets was squaring the cylinders to the heads. I just don't have a good way to locate them to pin them.
But now, it might just be that with the Indian head gasket being .012 thinner than the OE gasket, I can trim the head down to the right squish. Maybe. I have the cylinders at the shop being honed to the new pistons now. When I get them back next week, I will start the trial fittings and measuring.
And since I am making the base gaskets myself, I may be able to do a final tweek on the squish area and compression with different thicknesses there.............within reason. I know it also moves the ports but especially if the cylinders were moved up, wasn't that an old way to improve performance?
its going to be a minor if anything change, moving the ports that much..(or little).. you wont really feel anything. Unless you are ready to re-profile the squish area, the max id take out of the equation w out modifying the head would be .020" (out of the squish). 0.02
.020" max........noted.
The only reason I mentioned the thickness of the base gasket was because it could help getting the squish where it needs to be but won't affect the port timing enough to notice.
All good. I really appreciate you keeping me on the straight and narrow.
Hylomar is great stuff, but I try not to use it around solvents. It works great with oil. On quick change transaxles it's all we use for the rear two sections. We don't even reapply on assembly unless it's been totally wiped off. Anyways, pretty sure solvents remove it.
I just use 2t oil on gaskets. Of course everybody has their own method and that's likely because good mating surfaces will seal no matter what you put on there.
Agreed.
On things that I feel are likely to come back apart sooner rather than later (like the carb base gasket on a car) I also use oil or grease. If I don't think it is as likely to need to come back apart (like the RD cylinder base gasket) it gets the Hylomar. Like I said, I rarely if ever put a gasket on dry since I discovered the Hylomar. Just cheap insurance with no down side that I have found. And sometimes it will save the gasket for reuse due to it's ability to release. Which is another upside to using it on the cylinder base gaskets. No scraping required if the cylinders do need to come off. That by itself is enough reason to use it there.
And solvents like lacquer thinner are about the only things that will dissolve the Hylomar. Obviously, I really like the stuff.
I use copper spray on alot of gaskets my self. from my many years drag racing, carb base gaskets, rear end cover plates , header gaskets etc. stuff that comes apart alot. have used chapstick on carb base gaskets when tuning at the track tho. I tried this on my RD carb gaskets ( chapstick) because those jokers come of and on so often in this project. my2ct
ive done the chapstick trick under holley base gaskets myself, it does work well. Never crossed my mind for a cylinder base gasket for some reason. :thumbs:
I use Vaseline/petroleum jelly on gaskets for parts that get on and off a lot. Worked great on a 2600 V6 Capri head gaskets on engine with high compression pistons and full race cam along with valve cover gaskets and Holley 4bblon Offenhauser Dual Port intake...had a few burnt valves until jetting sorted.
Chapstick is mostly a combo of white paraffin wax and beeswax if you prefer to formulate your own in larger quantities. That's what I do. I also use Indian Head shellac gasket compound on gaskets, like carb base gaskets, clutch cover gaskets, etc that I need to remove easily but still get a good seal.