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Discussion Starter · #1 ·
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
 

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Well, all I can offer you here is what I plan to do myself, which is the TPUSA 904 kit. If you do that I see no real benefit to shaving the head. In fact from the info I have gleaned, the added compression is mighty fine anyway. Add to that the 813 cams, appropriate headwork for bigger valves and a set of FCR39s, and that is a kickass upgrade. That's my plan anyway.

I think if you shave the head you have to be wary of valve lift, but that can be dealt with of course.

That's my plan anyway. Cost effective? I think if you are into this kind of work, cost effective is not really the consideration any more.
 

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Well, all I can offer you here is what I plan to do myself, which is the TPUSA 904 kit.....
This is my exact plan too. I'm also planning to install a wideband to dial in the carbs throughout the build process. I'm watching craigslist for a used dyno cheap. New they are $8,000-$20,000 , I just hate being dependent on shops.
 

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You need to deside what you want to end up with in the end.First off forget about shaveing the head to rase C/R .If you do that later you wont be able to put bigger cams or big bore kit in pluss that changes cam timing.The 904 with good cams ,head and carbs will make the most hp.Plus you get brand new bores .The 865 kit is only as good as your bores are now.building these motors takes some planing ahead.What you need to look at is not what seams to be the best deal now but what will be the best deal 6 months or a year from now.With the 904 tpusa kit you have lots of room to make more hp.You can do the 904 and add to it as you get the money.The 865 may limit you to what hp you can make in the end.I am working on seeing how much hp I can get out of my tpusa 904,at ythis point I think 90 hp is with in reach,I dont think the 865 will ever do that do to the bore being to small to get big enough valves in it .If you only have enough money now go with the 904 now.If you can try and get a good head made up at the same time.Once you get the 904 and a good head you can add cams and carbs later with out much down time on your bike.
Ether way you go I will tell you the tpusa kits are first class.Mine runs smootherand sealed up quicker then the wiesco kit I had in there before.
 

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I'm also planning to install a wideband......
Getting your own dyno would be quite exciting and cool - a little over the top but depends on how much you do or are into it.

I installed an innovate wideband sensor, it really helped me dial in my carb settings on my recent airbox removal - bike runs and responds great. Now I have it in there and ready for the next upgrade.

As Mike says - plan ahead. I likely won't be able to do the whole 904 in one go, but I can maybe go carbs, then 904 kit, then head update, then cams and so on. That will be quite a lot of fun.
 

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Discussion Starter · #6 · (Edited)
Thanks guys there is some good advice.
Mike, thats a good thought about building the head at the same time! So you've had both 904 kits on your bike? Why the swap?
I wanted to ask about shaving the head, but wasn't considering it too hard.
I guess it comes down to the difference that 39cc's will make. If I got the TP performance kit (High comp pistons & cam, not the BB) then ill be that much farther ahead with the cam.
Ive read ALL the threads on it & bore condition is always mentioned, but she doesn't have many miles yet so I dont think that will be an issue.
I suppose my wish list is the same as everyone elses: BB, cams, carbs, bump rev limit, Nitrous....
S.
 

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All what you want sharp. dledinger just did pistons and cams and don't believe he has any complaints. But be sure to listen to Mike's point about the BB Nikasil kit. Those 39 extra cc's and .5 pt compression increase over the HC pistons allow for bigger valves...more options for future building. Yes those 39 cc's are pricey if doing 813 cams too...about 800-1000 more than HC pistons and 813 cams. So ask yourself what your future plans are. If you want the kind of horsepower Mike is talking, that is how you get there. I believe you can get 10 more hp or so with TPUSA's HC pistons and 813 cams only. If a stock motor is say 65hp...thats about a 15% increase in power which is still pretty substantial. All what you want. I wouldn't do Weisco based upon Mike's report tho...makes sene that the fresh BB Nikasil seals up tight and is the ticket. I too am surveying my options about these upgrades as well.
Cheers,
George
 

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Discussion Starter · #8 ·
Hmm Ill do a search for dledinger's bike.
Really the 904 feels like the way to go, but I would really like to see a comparison...
Where would a guy source 790 cams?
S.
 

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tpusa 813 are much better then 790 cams new 790 cams will cost you about as much allso.
I had a 989 wiesco stroker kit .I had trouble with the sleeves moveing.
 

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Wiesco BB

I have 3000 miles on my 904 Wiesco BB with no problems what so ever.
All what you want sharp. dledinger just did pistons and cams and don't believe he has any complaints. But be sure to listen to Mike's point about the BB Nikasil kit. Those 39 extra cc's and .5 pt compression increase over the HC pistons allow for bigger valves...more options for future building. Yes those 39 cc's are pricey if doing 813 cams too...about 800-1000 more than HC pistons and 813 cams. So ask yourself what your future plans are. If you want the kind of horsepower Mike is talking, that is how you get there. I believe you can get 10 more hp or so with TPUSA's HC pistons and 813 cams only. If a stock motor is say 65hp...thats about a 15% increase in power which is still pretty substantial. All what you want. I wouldn't do Weisco based upon Mike's report tho...makes sene that the fresh BB Nikasil seals up tight and is the ticket. I too am surveying my options about these upgrades as well.
Cheers,
George
 

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Some have good luck with the Wiseco 904cc ,some have trouble with leaks and sleeves moveing around.One thing to look at though the Wiseco 904cc kit is 10.5 comp. the tpusa kit is 11.5 comp. Thats about as much gain over the Wiseco 904cc as the Wiseco 904cc is over stock.Unless you have very bad fuel where you live the 11.5 is a gain.
 

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if I were to do a 904 kit now I'd go with TPUSA's kit.
Me too. Mike explained it quite well. It is technically challenging to get iron bores to mate precisely and stay in place. Part nominals have to be just right...correct amount of press...possible affect to cylinder roundness...different coef. of thermal expansion....iron doesn't wear as well as Nikasil...poorer cooling through iron sleeves...added weight of iron liners...yada. Plus...with TPUSA's Nikasil kit...don't have to send your jugs out to get bored etc. A lot less of a headache and should be better running with another point of compession as well. A no brainer really. The real question is whether to split the cases and add some crank throw. :)...but in any event, have to go with the 813 cams to work with that nice bump in compression.
George
 

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Discussion Starter · #16 ·
tpusa 813 are much better then 790 cams new 790 cams will cost you about as much allso.
I had a 989 wiesco stroker kit .I had trouble with the sleeves moveing.
What about a used set? Do cams wear excessively?
Here is a freebie for somebody. There is a head w/cams from an 03 America on FleaBay right now for $300...
So you could get used 790's & a wiseco kit for less than $1k (plus machine/install)
I think my first step will be to start looking at the shops around town & make sure I have somebody competent lined up to do the machine work. Plus see what they are charging. It may be that the machining cost will offset the added cost of the TP kit somewhat
S.
 

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To put the sleeves in will run you around $275 usa and if its not done right will cost you a set of jugs (new jugs are over $1300.)And yes cams do wear sometimes.Most of the 790 cams you will find will be the later ones there not as good and none of them are as good as the 813s.SAVE YOUR MONEY BUY THE GOOD STUFF .
 

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To put the sleeves in will run you around $275 usa and if its not done right will cost you a set of jugs (new jugs are over $1300.)And yes cams do wear sometimes.Most of the 790 cams you will find will be the later ones there not as good and none of them are as good as the 813s.SAVE YOUR MONEY BUY THE GOOD STUFF .
I agree with Mike...you're planning to replace the stock pistons/bump compression, so save your $$ for the hotter cams. Since your motor is a 270 degree version, I'm not sure how the 790 cams compare to other grinds or whether there's even a difference between earlier and later 790 cam offerings. Most of what has been posted on 813 cams has been related to the 360 degree motor, so someone with 270 degree motor experience with these cams should chime in here...

On stock piston, 360 degree motors, I'm pretty convinced that there's not a whole lot to be gained going to the 813 grind over the 790 cams. After adding 790 cams, my bike experienced equal HP and torque increase as the comparative dynos shown on the TPusa site for their cam addition to a stock piston 865 motor. However, for anyone who plans on going into the head/BB or changing pistons, the 790 cam seems to run out of legs based on Mike's/Carlos'/others experience and the 813 cam is a better choice.

My current position is to install the 790 cams if you plan to stay with stock pistons on a 360 degree motor....install the 813 cams if you plan/think you may go to HC pistons at some point. This assumes you can find some good condition used 790 cams/pick them up for about 1/2 what you would pay for the 813 cams...

Only you can say how serious you intend to get into building up your motor. I thought I was going to go HC to support the lumpier cam I wanted, but, after fitting the 790 cams, will likely shy away from getting into the motor since the cam does fine and didn't lose torque down low to gain HP up top. Better carbs and fine tuning will have me on the high side of 70 RWHP, which is a handful given my current suspension and brake specification. Better suspension to use the available power and putting the bike on a diet are the next focus...

Anyway, do what's sensible for you and your riding style. Most of all, enjoy the process of making your bike what you want it to be...

Cheers,

--Rich
 

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I would like more compression and more cam.(what dledlinger did) So it really comes down to which kit to go with. The TPUSA BB kit is pricey because of new Nikasil jugs. If not planning on doing much to the head, i.e. going with bigger valves and not going as extensive as Mike either will go or has gone...I think the best bang for buck for exacting another 10hp or so...perhaps a bit more...is TPUSA high compression pistons with 813 cams. To do the BB kit + 813 cams is almost another 1 large and again, unless going with bigger valves, the .5 pt of compression and 39cc's don't justify the price tag in my opinion.
Another 15% of power...say into the mid to high 70's for crank horsepower for 1 large with the HC pistons and 813 cams seems fair...another 1 large or so for 39 more cc's and .5 pt of CR which may equal another 3-4 or so more horsepower seems to be a bit heavy.
My thoughts...
George
PS: Now if TPUSA comes up with a 904 BB Nikasil + 813 cams kit with some savings versus buying separately...I would be interested. Hope they are listening.
:)
 

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Discussion Starter · #20 ·
I would like more compression and more cam.(what dledlinger did) So it really comes down to which kit to go with. The TPUSA BB kit is pricey because of new Nikasil jugs. If not planning on doing much to the head, i.e. going with bigger valves and not going as extensive as Mike either will go or has gone...I think the best bang for buck for exacting another 10hp or so...perhaps a bit more...is TPUSA high compression pistons with 813 cams. To do the BB kit + 813 cams is almost another 1 large and again, unless going with bigger valves, the .5 pt of compression and 39cc's don't justify the price tag in my opinion.
Another 15% of power...say into the mid to high 70's for crank horsepower for 1 large with the HC pistons and 813 cams seems fair...another 1 large or so for 39 more cc's and .5 pt of CR which may equal another 3-4 or so more horsepower seems to be a bit heavy.
My thoughts...
George
PS: Now if TPUSA comes up with a 904 BB Nikasil + 813 cams kit with some savings versus buying separately...I would be interested. Hope they are listening.
:)

Its like 6 of one, half dozen of the other... The piston cam kit, or the BB should both give about the same gains initially, its just where you plan on taking it after.
I didn't realize how undercammed the 865 is. Are the 813s a big change on both intake & exhaust, or is it more on the exhaust side?
And you are right! The BB + Cam kit would definitely be the winner!
S.
 
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