Slant heads with squishband

moonerdizzle · Jan 12, 2012

I was looking over the slant head from a motor I got recently that grenaded. I was planning on smoothing out the combustion area and noticed that there isn't a squish band on this head like there was on my older slanthead. I'll take pics of my old head next time I have it off. But I'm interested in seeing how many peoples slant heads have a squishband and how many don't.

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Sorry about the link to the photos, but my photobucket account is acting up.

Al.Fisherman · Jan 12, 2012

All 6 engines that I've bought came with a slant head (the way I ordered them). All heads has a squish band. Is that not a squish band on that head you posted?

nightcruiser · Jan 12, 2012

Al.Fisherman said:
All 6 engines that I've bought came with a slant head (the way I ordered them). All heads has a squish band. Is that not a squish band on that head you posted?

The head in the third picture appears to have a squish band...
All of my Grubee (2010) angle fire heads have had a squish band, fyi...

moonerdizzle · Jan 13, 2012

That is not a squish band, what appears to be a squish band is actually just a 1/16 of an inch or so lip in the material. My other head has a nice beveled squish band on it. I would take pics but I dont feel like taking it off and having to make another head gasket.

moonerdizzle · Jan 13, 2012

Also, all three pics are of the same head

biknut · Jan 13, 2012

Here's the 2 types I've seen on motors I've bought from BGF and LEB

biknut · Jan 13, 2012

biknut said:
Here's the 2 types I've seen on motors I've bought from BGF and LEB

The head on the right has the better combustion chamber, but I doubt they'll be much benefit from the squish band because there's too much clearance between the piston top and the head.

In order to have effective squish, you need a clearance of about 0.003". More than 0.004" and there's not much benefit. Much less than 0.003" and you run the risk of hitting the piston into the head.

Stock clearance is alot more than that. There are ways to make it less though. One way would be to mill the top of the cylinder down with sandpaper on glass.

The advantage of having proper squish, is anti piston ping, which allows for more compression, and thus more powwa. Throttle response becomes better too.

moonerdizzle · Jan 14, 2012

biknut said:
The head on the right has the better combustion chamber, but I doubt they'll be much benefit from the squish band because there's too much clearance between the piston top and the head.

In order to have effective squish, you need a clearance of about 0.003". More than 0.004" and there's not much benefit. Much less than 0.003" and you run the risk of hitting the piston into the head.

Stock clearance is alot more than that. There are ways to make it less though. One way would be to mill the top of the cylinder down with sandpaper on glass.

The advantage of having proper squish, is anti piston ping, which allows for more compression, and thus more powwa. Throttle response becomes better too.

The head on the right is just like the head I got on my motor right now.

talbotti · Jan 16, 2012

looks like with left head you will have more compression.

culvercityclassic · Jan 18, 2012

I have found the slant heads are really a poor design and do nothing to help performance. I have two bikes that run well with this head. Talk about a squishband...

biknut · Jan 18, 2012

culvercityclassic said:
I have found the slant heads are really a poor design and do nothing to help performance. I have two bikes that run well with this head. Talk about a squishband...

Without a lot of work I doubt you can get the squish band on that head close enough to the piston to help much.

talbotti · Jan 20, 2012

tomorrow im going to buy puch 75cc hi comp head, i take some pics when i get it mounted. brnot

culvercityclassic · Jan 20, 2012

Just a note: you need to get the 50cc one

skitchfish · Jan 20, 2012

culvercityclassic said:
Just a note: you need to get the 50cc one

Is it a matter of piston shape as to why you would not want to use the 74 cc head. It would seem to be better because it is actually made for 47 mm bore.

biknut · Jan 20, 2012

I can see a problem with the shape of the piston crown, and the shape of the squish band. They have to be made to match each other. If the angles are different that's not going to work very well.

biknut · Jan 20, 2012

biknut said:
I can see a problem with the shape of the piston crown, and the shape of the squish band. They have to be made to match each other. If the angles are different that's not going to work very well.

I'm not saying it won't work, it's just that the squish probably won't be able to be set tight enought to get much/or any squish effect.

talbotti · Jan 21, 2012

heres my new head vs stock head, it has much bigger fins so it should run cool

talbotti · Jan 21, 2012

oops forgot to upload images

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ImageShack® - Online Photo and Video Hosting

and i have to drill the head bolt holes bigger but do they have be 10mm holes (stock head has 10mm holes) studs are 8mm . maby i first drill tem to 8mm and if it doesnt fit i drill to 10mm. but now im going to buy myself a 8mm drill bit.

headtrama · Jan 30, 2012

In all honesty the puch head is a good cheap investment and works pretty good . The piston might nor fit the head perfectly but there is still a increase in performance over a stock head . Not only do you get a compression increase but also better cooling with the bigger fins . Also the stock heads are never flat I have mllled them flat to just have them start to blow head gaskets because now they are to thin . I am now squaring up the top of the cylinders because they are not flat at all as well .
If you want to invest some money into a cheap part that you will feel a difference with then the puch head is the way to go . I have three of them on three different motors and I have noticed a increase in performance on all three motors . These are not racing motors they are built loose and sloppy .So anything you can buy cheap and bolt right on and feel a difference is a win win .

MotorBicycleRacing · Jan 30, 2012

biknut said:
I can see a problem with the shape of the piston crown, and the shape of the squish band. They have to be made to match each other. If the angles are different that's not going to work very well.

I agree with that.
Aside from the MM head the only other head I have found that
does that is from www.ArrowMotorizedCycles.com which modifies the
standard head to include a squish band.

Head with squish band on the left.

droc089 · Jan 30, 2012

MotorBicycleRacing said:
I agree with that.
Aside from the MM head the only other head I have found that
does that is from ArrowMotorizedCycles.com which modifies the
standard head to include a squish band.

Head with squish band on the left.

Nice site, and that head looks killer. Can't wait to start working again, damn cows need to hurry up! lol

Slant heads with squishband

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