Author Topic: So, just when I thought I had all my problems fixed......video (Read 26981 times)

etccb · « **Reply #30 on:** March 11, 2015, 07:04:15 PM »

If you are wanting to keep the cases together right now there is no case mods required for a 310 or also a lot of guys run a bolt on 330. They have less bores avail but I would run a bolt on 330 if I needed to. I am not afraid of them and have seen some run very well.

Jimbo45 · « **Reply #31 on:** March 11, 2015, 07:08:57 PM »

I have another stock head (from the '88 top end that actually came with this sleeved cyl I bought used) I could try with a new stock sized head gasket, for the time being. How bad is that? Using a Tusk OEM style 66mm head gasket on a 69mm bore. Just for the time being, to see if it leaks, and maybe ride until I get my other top end either redone or buy another kit altogether?

Jimbo45 · « **Reply #32 on:** March 11, 2015, 07:11:02 PM »

Quote from: etccb;51427

If you are wanting to keep the cases together right now there is no case mods required for a 310 or also a lot of guys run a bolt on 330. They have less bores avail but I would run a bolt on 330 if I needed to. I am not afraid of them and have seen some run very well.

Can you point me towards some of those bolt on options, keeping in mind top horsepower is not a priority to me, but reliability and longevity is. Oh, and cost...that is a facter as well. LOL. Thanks for the help guys!

Pumashine · « **Reply #33 on:** March 11, 2015, 07:26:02 PM »

I would just send the cylinder and head to get them machined flat. Cometic sells a 68mm and 72mm 1 piece head gasket for the 250r. I think they have a 69mm also I just don't see it on ebay. They make the gaskets from scratch, so they are not just the stock one altered. Should be the cheapest most reliable fix. Proly only need to get the cylinder evened up. You can sand the head yourself with sand paper laying on a flat surface.

Jimbo45 · « **Reply #34 on:** March 11, 2015, 07:28:50 PM »

Quote from: Pumashine;51433

I would just send the cylinder and head to get them machined flat. Cometic sells a 68mm and 72mm 1 piece head gasket for the 250r. I think they have a 69mm also I just don't see it on ebay. They make the gaskets from scratch, so they are not just the stock one altered. Should be the cheapest most reliable fix.

Are the Cometic fiber gaskets the same as the Wiseco ones? Because I tried two of those, and coolant dribbled down the cylinder with those. Is that what you guys are using on over bores....the fiber Cometic and Wiseco gaskets?

Jimbo45 · « **Reply #35 on:** March 11, 2015, 07:30:06 PM »

Quote from: Pumashine;51433

I would just send the cylinder and head to get them machined flat. Cometic sells a 68mm and 72mm 1 piece head gasket for the 250r. I think they have a 69mm also I just don't see it on ebay. They make the gaskets from scratch, so they are not just the stock one altered. Should be the cheapest most reliable fix. Proly only need to get the cylinder evened up. You can sand the head yourself with sand paper laying on a flat surface.

Oh, and where do I send them to get them machined flat? If the cyl is machined shorter, then do I have to worry about the piston too high in the bore, and need a thicker than normal head gasket?

Jimbo45 · « **Reply #36 on:** March 11, 2015, 07:38:29 PM »

I am out to the garage to take this sumbish apart. Again.

Pumashine · « **Reply #37 on:** March 11, 2015, 08:34:48 PM »

Quote from: Jimbo45;51436

I am out to the garage to take this sumbish apart. Again.

Pull the head and check to see where the piston is at top dead center. If you take .010" off the top of the cylinder to make it straight, you just need to make sure your rings are not going to go over the top. Take a close pic at TDC.

Jimbo45 · « **Reply #38 on:** March 11, 2015, 09:45:28 PM »

Quote from: Pumashine;51438

Pull the head and check to see where the piston is at top dead center. If you take .010" off the top of the cylinder to make it straight, you just need to make sure your rings are not going to go over the top. Take a close pic at TDC.

Will do.

I just got done working the '88 head that came with this cylinder. Most will balk at this, but poor people have poor ways.... the head had some deep scratching, so I took a new piece of clean 220 grit wet paper, and put it on a piece of glass on my flat countertop. I lapped this head in circles, turning it 1/6th of a turn every fifty orbits, for several rounds. After checking, I could see where it was sanding down in all areas but two. It was warped for sure. So, I continued, until all was sanded out, and it has a uniform smooth flat face. Looks beautiful. I know its not like precision machining, but I bet its dam close. I will get a pic of it before I put it on.

Anyway, I am gonna swap this head I just lapped, and either re use the gasket that is on there (I know, I know), or should I use the new OEM gasket I have, even though it is for a 66-67mm instead of this 69mm? I know none of this is ideal, but I am definitely on a budget, and just want to make it run until I can either get my other top redone, or buy a 310 kit.

Pumashine · « **Reply #39 on:** March 11, 2015, 09:55:34 PM »

Quote from: Jimbo45;51443

It was warped for sure. So, I continued, until all was sanded out, and it has a uniform smooth flat face. Looks beautiful. I know its not like precision machining, but I bet its dam close.

Anyway, I am gonna swap this head I just lapped, and either re use the gasket that is on there (I know, I know), or should I use the new OEM gasket I have, even though it is for a 66-67mm instead of this 69mm? I know none of this is ideal, but I am definitely on a budget, and just want to make it run

As long as the piston does not hit the smaller ID of the OEM gasket you are fine. You only have a problem if the piston travels beyond the top of the cylinder and hits the gasket. I use the poor mans head flattening technique all the time. Works freaking perfect.

Jimbo45 · « **Reply #40 on:** March 11, 2015, 09:58:52 PM »

Quote from: Pumashine;51446

As long as the piston does not hit the smaller ID of the OEM gasket you are fine. You only have a problem if the piston travels beyond the top of the cylinder and hits the gasket. I use the poor mans head flattening technique all the time. Works freaking perfect.

You should see this head I lapped. It is a thing of beauty. I am fairly confident it is as true as about any stock head would be. Headed out now. Will post an update.......

etccb · « **Reply #41 on:** March 11, 2015, 10:27:15 PM »

Sweet
Give it a go.
Hopefully you can get it running until you are ready to do whatever you want to do next.
Good luck....

Jimbo45 · « **Reply #42 on:** March 11, 2015, 11:46:53 PM »

Well, I have it apart. I learned a few things.....

Here is the head I took off......obvious where the combustion gases were leaking into the coolant passage.....

Here is the shot of the deck before I wiped anything off (no sign of gases leaking on the cyl side of the gasket).....

Here is the head side of the gasket where the pressure leak was. Notice how it is right in the middle of the front water passage. Hmmmmmmm.......

Why was that pressure leak right in the middle front of the head? Well, see that little smashed part of the brass rivet that holds the gasket layers together?........

The smashed rivet even made a part circle mark on the outside edge of the head:

Interesting. I am assuming the dam rivet held up the head in that spot, and made the gasket not seal. It is obvious to me. Look even the rear rivet has a smashed part where it got smashed in between the head and cylinder.....

Lesson that I learned......OEM style gaskets are great, but you need to remove the rivets or at least cut away part of them, so they don't get wedged in between the head and cylinder.

Why is this not happening to anyone but me?

Tony, here are some pics I took of the deck height, above the piston at TDC. I didn't measure, but it appears there is at least 1/16". I put my new OEM gasket on there, and held it down hard with my thumb, and it appears it has good clearance from the piston, so I am gonna put the new OEM style 3 piece gasket 66mm gasket on there with the head I just lapped, AFTER I REMOVE HALF OF THE RIVETS, and CROSS MY FINGERS!

Here is the head I hand lapped:

Pumashine · « **Reply #43 on:** March 11, 2015, 11:58:18 PM »

Those rivets are not OEM. Looks like cheaper junk. http://www.ebay.com/itm/New-Top-End-Head-Gasket-Kit-Honda-TRX-250R-1986-1989-86-87-88-89-/360972295369?pt=Motors_ATV_Parts_Accessories&hash=item540ba01cc9&vxp=mtr Honda would not build interference into their parts. Is the head you just pulled off cut to 69mm also? You might want to put the head you lapped back on with an OEM gasket without rivets so the gasket is the same diameter as the head. You proly already got that figured out.

Jimbo45 · « **Reply #44 on:** March 12, 2015, 12:04:57 AM »

That head I have pictured above that I just lapped was the one that came on this 69mm cylinder. I suppose it is cut to match, IDK. I had swapped to the '86 head (with the pressure leak), because of an external coolant leak originally with the '88 head.

I am going to put this '88 lapped head on with the new Tusk OEM style 3 piece gasket I have, after I cut the rivets away. I think that may work actually.

The ground "OEM" gasket I bought looks identical to the Tusk one I have here, rivets and all. I don't think the ground one I purchased was made by Honda. It appears that it was Tusk. Might be a good gasket, but those rivets are a problem!!!!!!!!!!