Triumph 675 Forums banner

Performance Gain/ Reliability of kit gasket on bone-stock motor

6K views 46 replies 9 participants last post by  horra 
#1 ·
Good morrow gentlemen!
Do any of you guys have experience installing a kit gasket on the stock engine without any valve / spring / cam / crankshaft replacements?

I have been doing some research and it seems like exhaust valve is a weak point on 675 (look up sportrider daytona build). Is there significant performance gain from using a kit gasket or is it just 1-2hp gain at max?

Would running a race fuel (VP U4.4) help with stabilizing the engine?

My bike is getting race alternator installed and I was curious as if it's worth getting into as gasket itself is not that expensive.

Cheers
 
#3 ·
:cool2:
HEY This is my winter project!
What accompanying mods did you do?
any chance i can get your cam timing specs, was told stock is good?
also what adjustable cam sprockets did you use?
 
#7 ·
If you're pulling the head and going to top end power, i would recommend the kit valve springs. Just note, that they only good for one season (as with most valve springs).

I'm trying to get APE in California to try an develop a set of race springs for the 675. Should be half the cost of the kit springs, I hope.

They also make a stronger spring retainer as well, but not for the 675 (yet)

Oh, and Markbuilt did my head re-assembly after I F'd up the valve shims. Dynoyed at 123 RW with the rev limiter stuck on 12K. We figured another 5HP is there once I figure out the issue with the rev limiter. Pulled really strong on the track, but hitting that rev limiter was not fun.

Pump gas as well.
 
#8 ·
If you're pulling the head and going to top end power, i would recommend the kit valve springs. Just note, that they only good for one season (as with most valve springs).

I'm trying to get APE in California to try an develop a set of race springs for the 675. Should be half the cost of the kit springs, I hope.

They also make a stronger spring retainer as well, but not for the 675 (yet)

Oh, and Markbuilt did my head re-assembly after I F'd up the valve shims. Dynoyed at 123 RW with the rev limiter stuck on 12K. We figured another 5HP is there once I figure out the issue with the rev limiter. Pulled really strong on the track, but hitting that rev limiter was not fun.

Pump gas as well.
Oh dear te he he. You know what, my friend has been working with Mark for a while te he he he (that's where he got his 675 tuned)... I also got my 675 tuned there :) great stuff... Mark also installed my attack rear sets when he did the dyno.

However, attack has a design flaw: few of the screws are too short. I have seen three separate Daytonas (including mine) whose Attack Rearsets connecting bolt just came loose on the track...

Mark fixed it up for me for free when I popped by his shop between sessions.:thumbup:

So the valve strength is not an issue?
 
#9 ·
I think most of the failures I seen/read about where retainers and springs/spring pockets. At high RPM, the valves can float without proper tension. But to be honest, this is true with most modern race engines.

But the point to make is 'race engines'. These are motors that spend most of their time above 12K, and are pushed way beyond that. In other words, the more you rev, the more stress the valve train is under.

Same holds true with rod bearings. Valve train, rod bearings and rods are typically goes when a 675 blows up. On the other hand, pistons and cranks seem to hold up just fine. Your results and millage may vary ;-)

I really don't think this is a major issue with 90% of the track day or amateur racers out there. Just those pushing the limits or have warn out motors.

I also believe that most amateur racers don't refresh their motors as often as they should. Even Triumph states that their race kit springs should be replaced each season. It's the whole "a light that burns twice as bright will only last half as long" theory.
 
#10 ·
I think most of the failures I seen/read about where retainers and springs/spring pockets. At high RPM, the valves can float without proper tension. But to be honest, this is true with most modern race engines.

But the point to make is 'race engines'. These are motors that spend most of their time above 12K, and are pushed way beyond that. In other words, the more you rev, the more stress the valve train is under.

Same holds true with rod bearings. Valve train, rod bearings and rods are typically goes when a 675 blows up. On the other hand, pistons and cranks seem to hold up just fine. Your results and millage may vary ;-)

I really don't think this is a major issue with 90% of the track day or amateur racers out there. Just those pushing the limits or have warn out motors.

I also believe that most amateur racers don't refresh their motors as often as they should. Even Triumph states that their race kit springs should be replaced each season. It's the whole "a light that burns twice as bright will only last half as long" theory.
That sounds like a pain... I am kind of being turned off by kit gasket :) On the other note, would racing fuel such as VP4.4 increased the compression and lead to more engine wear and tear? I just don't understand where all those extra hp's produced by race fuels come from.
 
#12 ·
Fwiw, my bike made 114.5/47.2 on pump gas...119.85/49.5 on u4 with 1 more degree of timing and a touch less fueling on top end...

I am on the east coast, but I'm in s Florida....

I am running kit springs also...the builder notched my stock sprockets and advanced the cams 6*.....similar to what he does on gsxr's as the cams spec'ed out similarly....

The bike is an animal. I could easily yank worked 600's at Daytona....
 
#35 ·
.

I am running kit springs also...the builder notched my stock sprockets and advanced the cams 6*.....similar to what he does on gsxr's as the cams spec'ed out similarly....

The bike is an animal. I could easily yank worked 600's at Daytona....
Both cams advanced 6 degrees? That seems like a lot!

Where do yall get your small parts from? I was wanting to do the springs in the off season to be on the safe side, and it seems the price of the springs, gaskets, bolts, etc starts to add up pretty quick.
 
#13 ·
Oh, and yes, I'm still SS legal...

The full rundown on mods is:

Bmc race/hord stacks
Akrapovic full system(now changed to an Arrow after my off at Daytona)
Kit stator/springs
Degreed cams/gasket/valve jod(0 port work!)
U4 with a badass tune via Tune ecu....
 
#21 ·
Ahhh fackers... I just got my kit alternator... hmm so changing out the valve spring shouldn't be an issue... but on the other hand,
Degreed cams valve job are allowed? Don't they require machining the original parts?

(3.) Original equipment head, valves, and cams must remain as produced, with the exception of machining the gasket surface of the cylinder head.

I am no mechanic so I am bit confused here... when they mention allowing the cylinder head machining does that mean port and valve seating is allowed?
 
#27 ·
So let me get this straight:

CCS Supersport -
No Porting
YES to cam timing/ valve job, velocity stacks and kit alternator

WERA Superstock -
No Porting or Kit Alternator
Yes to cam timing/ valve job, velocity stacks

Is that correct?

Where do they stand in terms of rear subframes and rear linkage? I have yoyodyne rear subframe and only thing it's missing is a strut for rear passenger.

God damn it why are all the rules facking different?
 
#32 ·
CCS for me.....Wera is nowhere near close enough...

Fwiw, I run GTU, mwss, mwsb, Hwss, hwsb, and mwgp. It's usually all the same bikes but there is no tech if you podium in the non-SS classes...
 
#34 ·
Remember, dynos are just a tuning tool....there has only been one other 600 to dyno 120 whp on the dyno where mine made 119.85....

The dyno is very pessimistic and sees its fair share of AMA bikes....Mesa, Villa etc....
 
#36 ·
I have a local Triumph dealer as a partial sponsor, so he usually helps me out with pricing...

Iirc my builder said he went 6*....he also said the stock springs aren't strong enough for stock cams at max lift! The kit springs spec'ed out just right for the stock cams...in his opinion...

He usually builds some badass suzukis...he was impressed with the 675!
 
#38 ·
Pardon my ignorance guys but what exactly is involved in a ' valve job"? Is this the same as valve lapping or is there something else involved.

I am thinking about getting a custom tune but want to make the most of it and though that bumping up the compression with a thinner gasket and perhaps even shaving the head or decking the block to make the most of it all might be a good thing in terms of making a little more power. Are these the types of mods that a 675 responds well to or am I better off doing something else?
 
#39 ·
"valve job" can mean different things to different people. It could be as simple as lapping the valves, machining the face and valve seat, or a "multi angle" regrind which improves flow at low lift. You really need to talk with the guy doing the work to find out exactly what you are getting.
 
#40 ·
"valve job" can mean different things to different people.
Yes I know. That's why I asked. A few people have posted in this thread about doing a valve job. I just wanted them to be a little more specific before I make a Dick of myself while talking to an engine builder.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top