slant head dead

wezwheels

wezwheels

New Member
the design is and has a flaw. the way the plug sets in the head causes an over heating of one side of the piston top. the plug does not fall in at top dead center. an unequal heating of the piston top causes a weld splatter effect over time. the piston top is getting hot on the one side and not distributing the heat over the whole piston. which starts a melting or a splatter of the metal on the top of the piston. the splatter builds up and causes it to gouge the cylinder and piston. the gouging has lead to the splatter getting down to the rings and jamming the rings in there slots. before you ask or tell yourself i`m and idiot, the oil ratio is a 16/1 to a 20/1. the denso plug is equal to the ngk b6hs. so its not a hot plug or a lack of oil that caused the issue. just a poor design? or am i missing something? you decide? thanks again. wez. :-||
 
The slant heads are small, warp easily and aren't the best design.

I must ask, more importantly - how was your air:fuel ratio?
 
Is you fuel mix too lean causing it to run hot? What did your plug look like when you pulled it out? White? Brown?
 
this one has about 600 miles on it. the other non slant heads have 1700 miles with out piston issues. i`m a daily rider.
 
no, i ran a 20/1 ratio. the plug is a dry brown. no oil build up. i hope that the seller will look out for me. just got the motor a couple of months ago. will see how they back up there warranty? i think i may already know there answer? not to many places stand behind there warranties.
 
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The logic behind the flaw makes sense, now I am worried that my slant head may be in trouble. Has anyone else pulled there head to check this? Mine might have 200 miles on it if I am lucky so I am not sure if pulling it would tell me anything, but it should make until winter when I plan on rebuilding it.
 
What about detonation (ping)? These engines are rather noisy, maybe it was pinging and you did not hear it. Just thinking.

Sorry, I meant pre ignition. Detonation happens after the plug has fired.
 
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So my question is, is it possible to put a regular head on a slant head engine? or would you have to change the piston and/or cylinder too?
 
we need to keep this thread going,i have always been impreesd by grubees quality but i just finished my first slant head build and havent got it tweaked yet, living at altitude i run pretty lean well real lean, shoot i bought 3 of these mills when i get this one going good ill update as to what i see
 
I bought my slant head from zoombycles and i have at least over 600 miles on it. iv been riding pretty hard in triple digit weather and my motor has been okay. just thought i would throw in my 2 cents
.bf.
 
I must say, I am seriously thinking of putting my slant head back on....I miss the power....hate the warping....

I am also going to first try milling my stock hemi head as much as possible first.
 
I have had only one slant head. Three buddies have them never came across warping? Not saying it is impossible just puzzling? Manic Mechanics head will not warp I got one. That thing is solid.
 
I dunno, it came warped, I lapped it flat. It warped with usage. Lapped it perfectly flat again and it warped again. It wows up in the section under the plug.
 
i decided to do a little testing with mine today.

my 24" has a Grubee GT4 with the flat head, and i built up a GT5 on a new bike. the new bike doesn't have the out-of-the-box power the GT4 has, so i decided to bolt up the slant to my GT4.

i can honestly say that it was slower all the way around the powerband. accelerated slower, lower top speed, just all around slow.

i'm not talking a mile or two slower, i mean like 5-10mph slower. my bike can run all day at 45+, but with the slant, it wouldn't keep up with traffic.

i know the head wasn't warped when i put it on, and it ran smooth the whole time, it just didn't have any of the power that everyone claims.

haven't taken it off yet, so i dunno if it was running lean or anything, i'll check it tomorrow.

but overall, i don't like it.
 
You guys are killing me here!

The plug was put in at an angle in order to clear the top tube of frames that might of otherwise been unsuitable for an engine installation.

About a year ago, forum hype gave credence to the slant head. Just as a matter of coincidence it had a slightly better chamber shape...And I do mean slightly! These engines are so archaic that it would not make any difference where the plug was located in the cylinder head.

Jim
 
NOW you tell me...

this is one of those rare cases where i didn't do my research, and just went by what the manufacturers and advertising claimed.

i just read chapter 2 of Graham Bell's Two Stroke Tuning (http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf)

he says that a slant head (without a rear offest combustion chamber) causes the end gases to detonate, creating excessive heat, warpage, and potential total engine seizure.

so, anyone wanna buy a slant head?
 
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