Frankenstein 701 questions

[Scraggly]

I am about to assemble a 61x/62t engine. A few things i have been thinking about are running no base gasket and just yamabond. I am assuming this will kill my squish tolerance, anyone know what i will loose? I am thinking around 0.030.
I also have a sport port template, and dose this work as well with the T cyl as with the X cyl? playing around with the templates the exhaust height is not far off about 1-2mm. would the porting be better to align with the top of the cylinder or with the top of the port window?
Im just brainstorming and looking for a little input. what have you run with this combination? and what did you think?

Thanks
Matt

 

[Crab]

T cylinder is like pre ported...lol.

 

[Scraggly]

it looks a lot cleaner (port matching) then my x does

 

[Waternut]

I'm planning on putting my cylinder back on with no base gasket. The gasket is 0.020". I've read that it produces good results on the kawi's but not sure on the SJ's. I'll let you know pretty soon.

 

[Mark44]

If you do that you will need to check squish.

Mark44

 

[Scraggly]

If you do that you will need to check squish.

Mark44

im going to do that before i try and run it, just curious if anyone has done this and what happened. btw its a east coast cycles billet head with 35cc domes.

bore measured 82.55mm

 

[Waternut]

Just measure my squish after assembling my engine without a base gasket. Still waiting for the yamabond to cure before doing a leak check on it though.

I'm getting a little fluctuation since I had to lightly buff the high metal off my head caused by the crank bearing failure. Anyway, most of the measurements I took were between 0.045" and 0.048" and I got 0.043" and 0.060" once. I'm thinking the 0.060" was because I didn't get it all the way to the edge of the cylinder though. I'm no engine builder but from what I've read, 0.045" is a good number. Please let me know ASAP if it isn't though!

 

[Idok]

I am about to assemble a 61x/62t engine. A few things i have been thinking about are running no base gasket and just yamabond. I am assuming this will kill my squish tolerance, anyone know what i will loose? I am thinking around 0.030.
I also have a sport port template, and dose this work as well with the T cyl as with the X cyl? playing around with the templates the exhaust height is not far off about 1-2mm. would the porting be better to align with the top of the cylinder or with the top of the port window?
Im just brainstorming and looking for a little input. what have you run with this combination? and what did you think?

Thanks
Matt

I have thought about this myself in the past..always wanted to try it with a 650 motor..

it just makes me slightly nervous


I had a 1/5th scale RC car (HPI baja) and I burned up the basegasket on it...I just took it out, and slammed it (no yamabond though, shoulda in retrospect)...it didnt hold up very long...actually, the cylinder headbolts vibrated loose

apples and oranges, but..

 

[BruceSki]

I have thought about this myself in the past..always wanted to try it with a 650 motor..

it just makes me slightly nervous


I had a 1/5th scale RC car (HPI baja) and I burned up the basegasket on it...I just took it out, and slammed it (no yamabond though, shoulda in retrospect)...it didnt hold up very long...actually, the cylinder headbolts vibrated loose

apples and oranges, but..

lol i did that with a hedge trimmer a couple years back. leaned it out a couple turns on the high too. did all my customers hedges in one day---it ripped----must have been revving a thousand rpms or so higher than usual.

they next time i went to use it, it vibrated the cylinder bolts loose and shot the cylinder right off the case.

but it did run like an animal for that one day.

 

[Waternut]

Man you guys aren't inspiring confidence in me. All of my engines are notarious for rattling bolts out.

 

[Waternut]

Alright running no base gasket with 35cc domes is way too much for pump gas. Before hooking everything up, I did a quick compression check. 210psi... Never would've guessed 0.015"-0.020" would make that much of a difference.

PS - I didn't have the pipe on though so I don't know if that makes a difference.

 

[ATS_Aaron]

The pipe should not make difference in a compression test.

 

[SUPERTUNE]

Man you guys aren't inspiring confidence in me. All of my engines are notorious for rattling bolts out.

Maybe you should invest in a Snap-On or Proto torque wrench.

 

[Idok]

lol i did that with a hedge trimmer a couple years back. leaned it out a couple turns on the high too. did all my customers hedges in one day---it ripped----must have been revving a thousand rpms or so higher than usual.

they next time i went to use it, it vibrated the cylinder bolts loose and shot the cylinder right off the case.

but it did run like an animal for that one day.

exactly. what happend with my car....when I first did slammed it the thing woudl wheelie all day long (and were talking about a 35lb car)....but it only ran like that 2-3 tanks

Man you guys aren't inspiring confidence in me. All of my engines are notarious for rattling bolts out.

you have other issues then.....do you have a torque wrench?

if you got that much compression, I'd check the dome to make sure that the piston is not hitting it!

we had a one a couple of years ago just like that and the piston stamped all the markings into the dome lol..

 

[SUPERTUNE]

Alright running no base gasket with 35cc domes is way too much for pump gas. Before hooking everything up, I did a quick compression check. 210psi... Never would've guessed 0.015"-0.020" would make that much of a difference.

PS - I didn't have the pipe on though so I don't know if that makes a difference.

Don't you have MSD TL? 210 lbs will be fine if you do, just make sure you have enough retard at the higher RPMs.
Yes, you can pick up compression quick when you have higher compression.
Is this a fresh assembled top end and not been run yet? If so, then the assembly oil will give you a higher than normal reading.

 

[Waternut]

Don't you have MSD TL? 210 lbs will be fine if you do, just make sure you have enough retard at the higher RPMs.
Yes, you can pick up compression quick when you have higher compression.
Is this a fresh assembled top end and not been run yet? If so, then the assembly oil will give you a higher than normal reading.

I do have TL but went ahead and dropped a base gasket back in there for my own piece of mind. The assembly oil did make quite a bit of difference though. I think my compression was around 195psi after adding the gasket and then went back down around 175-180psi after it had been run a couple minutes. Maybe I would've been ok after all but it's done now...

For future reference, at 210psi cranking compression, how low would I have to retard the timing to keep it from messing up with pump gas?

 

[SUPERTUNE]

I do have TL but went ahead and dropped a base gasket back in there for my own piece of mind. The assembly oil did make quite a bit of difference though. I think my compression was around 195psi after adding the gasket and then went back down around 175-180psi after it had been run a couple minutes. Maybe I would've been ok after all but it's done now...

For future reference, at 210psi cranking compression, how low would I have to retard the timing to keep it from messing up with pump gas?

Set the dip switches to start sooner and add more rate retard...

 

[Rickster]

im going to do that before i try and run it, just curious if anyone has done this and what happened. btw its a east coast cycles billet head with 35cc domes.

bore measured 82.55mm

I ran my bigbore with no base gasket for a year, and had no issues.. The reduction of squish was like .03"... That base gasket get's compressed pretty good...

 

[ryan]

i am running 210 on pump gas . WOT all day no issues.

 

[BruceSki]

i am running 210 on pump gas . WOT all day no issues.

stock ignition w MSD cdi -- 93 octane @ 32:1