 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
OP
Member
Joined: Jul 2008
Posts: 55 |
In the beginning the plan was for a 904.
Then TPUsa came out with there kit & some of the BB guys said that they would consider doing that if they had their time back, as you get the cams with it. So now that seems the way forward, as it was the higher CR that seemed to make the most difference. Especially with an 865...
The other option would be to buy the cams, shave the head for higher comp & then use the difference to go towards the carbs, or maybe raise the limiter.
Im obviously looking for the most cost effective way to proceed, but Ill definitely be going one of these routes
Opinions?
S.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jan 2005
Posts: 8,639 Likes: 3
Old Hand
|
|
Old Hand
Joined: Jan 2005
Posts: 8,639 Likes: 3 |
Increasing the compression can be good up to a point. If you go too far, you will need more radical valve timing to reduce the effective compression at low engine speeds to stop detonation.
Increasing the engine size does more than increase compression. A bigger bore adds square inches for the combustion pressure to push against, increasing the downward force and a longer stroke gives that force more leverage to twist the crank. As Racer Brown used to say, "The only substitute for cubic inches is more cubic inches".
Let's hope there's intelligent life somewhere in space 'cause it's buggar all down here. -- Monte Python
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jan 2005
Posts: 3,753
Loquacious
|
|
Loquacious
Joined: Jan 2005
Posts: 3,753 |
i would say shaving the head is not an option. thats my opinion tho. if you shave you will not be able to add larger valves in the future if you shoose, and i dont like the idea there is nothing you can do after its shaved. no way to reverse it. i went the weisco rt with the 904 and am plenty happy. i have about 5-6k on it and it runs like a top. more guys also have it. but the other kit seems good also. both people will vouch for what they have. just read as much as you can before you decide. and talk to guys like carlos and gatley
(Former)05 BA tbike pipes, ai removed, Freak, mikuni hsr 42's, 904, ported/polished head, 1mm oversized valves
NOW-2010 silver and black tbird
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
|
OP
Member
Joined: Jul 2008
Posts: 55 |
Shaving the head was a more extreme example that I probably wouldn't go with.
Just to clarify though, Im talking about the new TPUsa kit that has the high comp pistons & the cams, not their BB kit.
The reports seem like it really wakes her up, although I hadn't considered needing the big bore to get bigger valves later...
S.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Feb 2007
Posts: 23,227 Likes: 62
Fe Butt
|
Fe Butt
Joined: Feb 2007
Posts: 23,227 Likes: 62 |
Cams alone make a big difference in the 865 from what I hear. The higher compression pistons would too, I always ran 10.5:1 in the old Triumphs.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
|
OP
Member
Joined: Jul 2008
Posts: 55 |
Thats the other side of the coin isnt it?
Are the cams & higher CR a better bang for the buck then the 904 w/no cams?
S.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 1,440
Learned Hand
|
|
Learned Hand
Joined: Jul 2008
Posts: 1,440 |
Shaving the head also affects detonation because it modifies the quench area. That can cause a much greater tendancy toward detonation than the equivalent compression ratio achieved by changing pistons. I wouldn't want to be the first to do this to a motor, or to do it without knowing what the results will be, based on a thorough set of performance measurements. 
'08 America Blue/White; Custom Headlamps, Custom Lowers, Clearview 20", Bafflectomy
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
|
|
Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
My 865 is bone stock except for airbox elimination, carb tuning & long Tors.
My next mod is going to be 790 cams & a 3 degree advance.
Sometime after that, either bored-out CVK's or FCR's.
Then, maybe a BB stroker kit.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
|
OP
Member
Joined: Jul 2008
Posts: 55 |
What year bike will you try to get the cams from?
Can you get them new anywhere?
S.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jan 2005
Posts: 8,639 Likes: 3
Old Hand
|
|
Old Hand
Joined: Jan 2005
Posts: 8,639 Likes: 3 |
Cams from any 790 will work as long as they are for the 270 degree engine. The aftermarket cams from Thunderbike will do even better. If you do go with high compression pistons the Thunderbike cams may be best because the effective compression pressure will be a little lower at low speeds, reducing the chance of detonation.
Let's hope there's intelligent life somewhere in space 'cause it's buggar all down here. -- Monte Python
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
|
OP
Member
Joined: Jul 2008
Posts: 55 |
If I go aftermarket it'll be 813's
S.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Aug 2007
Posts: 10,730 Likes: 5
Should be Riding
|
|
Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 5 |
I'm getting a set of Fast Fred's cams, he says they are better than the 813's
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
|
|
Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Quote:
What year bike will you try to get the cams from?
Can you get them new anywhere?
S.
I'm not sure if this question was for me, however any 790/270 set should work. If I go that route I'll probably buy them from Bike Bandit, or look for a low-mileage take-off set from someone with a 790 who's "upgrading".
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
|
|
Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Quote:
...If you do go with high compression pistons the Thunderbike cams may be best because the effective compression pressure will be a little lower at low speeds, reducing the chance of detonation...
FWIW, my dyno guy tested T-Bike (NZ) and TPUSA 813 cams back to back on his 904/270, & the 813's made more power (1 more peak HP), all other things equal.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
|
OP
Member
Joined: Jul 2008
Posts: 55 |
This is the first I have heard of Fast Fred cams. Where do you get those? I tried google but the only likely website is 404
S.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Aug 2007
Posts: 10,730 Likes: 5
Should be Riding
|
|
Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 5 |
Fred has his own custom grind. Looks like his website got shut down, I know he's working on another right now... I'll be getting mine in a few weeks, will report more on them after the dyno run
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
|
OP
Member
Joined: Jul 2008
Posts: 55 |
Good to know! The more options for these bikes the better!
Looking forward to seeing your results
So what is one of his grinds running? I assume you need to send him your cams first?
S.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Aug 2007
Posts: 10,730 Likes: 5
Should be Riding
|
|
Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 5 |
He charges under 700 bucks for the re-grind, and you need to send him yours first. I don't know an exact cost, I have a whole package deal worked out with him for carbs, cams and intake manifolds
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Apr 2009
Posts: 48
Greenhorn
|
|
Greenhorn
Joined: Apr 2009
Posts: 48 |
Quote:
I'm getting a set of Fast Fred's cams, he says they are better than the 813's
Can be equal but not better, I know why and what I'm talking about.
1087cc's- 115RWHP-81.5RWTQ.Nuff Said
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Apr 2008
Posts: 3,937
Loquacious
|
|
Loquacious
Joined: Apr 2008
Posts: 3,937 |
Quote:
Quote:
I'm getting a set of Fast Fred's cams, he says they are better than the 813's
Can be equal but not better, I know why and what I'm talking about.
Enlighten us. 
And you may see me tonight
With an illegal smile
J. Prine
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Feb 2005
Posts: 988
3/4 Throttle
|
|
3/4 Throttle
Joined: Feb 2005
Posts: 988 |
Quote:
Quote:
Quote:
I'm getting a set of Fast Fred's cams, he says they are better than the 813's
Can be equal but not better, I know why and what I'm talking about.
Enlighten us.
Yes I would like to hear your reasoning.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Apr 2009
Posts: 48
Greenhorn
|
|
Greenhorn
Joined: Apr 2009
Posts: 48 |
We share technical data, Fred does our racing heads, since last year.
These are shim over bucket cams, 813's it's the max spec allow for that configuration.
Last edited by 1087; 05/17/2009 8:14 PM.
1087cc's- 115RWHP-81.5RWTQ.Nuff Said
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jan 2005
Posts: 200
Adjunct
|
|
Adjunct
Joined: Jan 2005
Posts: 200 |
I think that Fred does some headwork for TPUSA so thru this association they probably share information so the cams are quite likely ground to the same specs.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jan 2005
Posts: 200
Adjunct
|
|
Adjunct
Joined: Jan 2005
Posts: 200 |
I guess my theory was correct. I was just a little slow with the reply.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Feb 2005
Posts: 988
3/4 Throttle
|
|
3/4 Throttle
Joined: Feb 2005
Posts: 988 |
Quote:
I think that Fred does some headwork for TPUSA so thru this association they probably share information so the cams are quite likely ground to the same specs.
Well then that makes sense! 
Last edited by 69tri1; 05/17/2009 8:20 PM.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Aug 2007
Posts: 10,730 Likes: 5
Should be Riding
|
|
Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 5 |
Quote:
Quote:
I'm getting a set of Fast Fred's cams, he says they are better than the 813's
Can be equal but not better, I know why and what I'm talking about.
I know you do, I talked to Fred today about them and got the lowdown 
I'm not trying to step on your toes here Carlos
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Mar 2007
Posts: 5,616
Check Pants
|
|
Check Pants
Joined: Mar 2007
Posts: 5,616 |
OK Dave and/or Carlos...what are we not being told? 
SOLD: 07 Black BA, 39mm FCRs, TPUSA stage 1 head, TPUSA 813 cams, TPUSA 10.8:1 pistons, TTP #3 igniter, Specialty Spares Long Cannons, Tsukayu Hard Bags. 82HP/55tq
NEW: 19 Goldwing Tour DCT
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Aug 2007
Posts: 10,730 Likes: 5
Should be Riding
|
|
Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 5 |
All I know is that once upon a time, Fred told me that he starts with an 813 cam. Starts with one. There must be more to it. I don't know enough about it to say, just what he told me a while back... said it was better. Whatever it is, I guess it's the max you can run without the shim under bucket upgrade. I'm sure Carlos can chime in with all the technical aspects of it, that's not really my thing. I just get stuff that makes more power without really understanding what it does or why. And if it does, I'm a happy guy.
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Feb 2007
Posts: 23,227 Likes: 62
Fe Butt
|
|
Fe Butt
Joined: Feb 2007
Posts: 23,227 Likes: 62 |
My head is shaved but I don't think it makes my engine any different.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
|
OP
Member
Joined: Jul 2008
Posts: 55 |
Can somebody explain shim under/over?
Im still pretty new to this top end stuff
S.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jan 2005
Posts: 2,416
Oil Expert
|
|
Oil Expert
Joined: Jan 2005
Posts: 2,416 |
Quote:
Shim under bucket is a design that is most commonly used on high performance type engines. Its design lends itself to a lighter overall valve train and more accurate valve timing, thus a higher revving engine. The design consists of a bucket that fits over the valve stem and retainer and different thickness shims that are installed on top of the stem and the bucket is then installed over the entire assembly. This arrangement is somewhat involved to adjust as the camshafts must be removed to access the buckets and shims (the cam lobes ride on the buckets). This adds extra time and expertise to make sure the cams are put back into time during assembly. No real special tools are required, but an assortment of shims is a must.
Shim over bucket is basically the same idea as the shim under bucket although some designs are made so the camshaft(s) do not need to be removed. In this case a special tool is required to push the valve bucket down slightly so the shim can be removed. The camshaft in this case rides on the shim itself.
Google is your friend... 
"Wise men speak because they have something to say, fools because they have to say something."
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Apr 2009
Posts: 48
Greenhorn
|
|
Greenhorn
Joined: Apr 2009
Posts: 48 |
Spot on Piper!
Your post summarizes very well, what is all about it.
We can add that SUB it's for the ones that it really likes to have serious TQ and HP out of these motors,conserving a great reliability and good street manners.
Just in case Roadwhorty we have 15 different grinds for SUB configuration.
1087cc's- 115RWHP-81.5RWTQ.Nuff Said
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Aug 2007
Posts: 10,730 Likes: 5
Should be Riding
|
|
Should be Riding
Joined: Aug 2007
Posts: 10,730 Likes: 5 |
Sean, here is Fred's website if you're interested http://fastfredsheadworks.com/default.html
Always remember to be yourself. Unless you suck. Then pretend to be someone else.
|
|
|
Re: 904 vs TpUsa Kit vs Shaved Head...
|
Joined: Jul 2008
Posts: 55
Member
|
|
OP
Member
Joined: Jul 2008
Posts: 55 |
Very interested! Looks like some good work
Thanks
S>
|
|
|
|
|
