Author Topic: what would/did you build on a semi budget?  (Read 795 times)

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Offline jaguar

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what would/did you build on a semi budget?
« on: March 15, 2011, 10:54:03 am »
im looking for input on a motor build for my K1.  Im looking for something that falls into the "best bang for your buck" category.
I want something fun for the road.

i dont want something that needs thousands of dollars for rods and such.

would a cam and 836 kit be the way to go?
standard bore with some other work?

i do understand that speed costs money.....
im thinking under $2000 on the motor?  maybe under $1500?

where do the stock rods become the weak link?
how far do the stock carbs go?

Offline jaguar

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Re: what would/did you build on a semi budget?
« Reply #1 on: March 15, 2011, 11:09:28 am »
i was kind of thinking the APE kit with a yoshi rep pipe.
would the stock rods be ok for that?

Offline Jim F

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Re: what would/did you build on a semi budget?
« Reply #2 on: March 15, 2011, 01:51:24 pm »
I run a 836 and a mild street cam
some porting with heavy springs
Dyna S ignition and Dyna coils
Stock rods and this motor is about 20 years old with no problems
I probably have a little over $1000 in (20 years ago)

good luck

Jim
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Offline jaguar

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Re: what would/did you build on a semi budget?
« Reply #3 on: March 15, 2011, 01:57:51 pm »
well i figure the big ticket items in a real crazy build are the rods and the carbs.
to keep cost down i would like to keep the stock rods and carbs but on the other hand dont want to start braking every other day.

so in my head i have two options to explore.

1
replace the carbs with CRs or something and run a standard bore
OR
2
run the stock carbs and bore the motor


at the lower HP numbers im thinking would i be just as good to run a cast piston like the cycle X?

Offline MidnightLamp

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Re: what would/did you build on a semi budget?
« Reply #4 on: March 15, 2011, 02:19:22 pm »
A budget build for me would involve:

CB360T pistons (4th over) or 850 pistons from cycle X on a stock sleeve cylinder....around $300 with boring either way.
Master Rebuild set - $150 for every last bit that you need (seals, gaksets, etc..)
Ported/Polished head with polished stock valves - free + labour
F3 camshaft - $30?
Stock rods, polished + cryo (not bead blasted) + balanced, with new F2 bolts - $100
Bearing kit $80 for rods, $100 for crank, clearance correctly.

~$760

But this would involve you making sure that the: primary drive is OK, guides are OK, cylinder surface is OK, trans is OK, and much more.
'75 CB750 - Racer
'69 CB350 - Racer
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'74 Commando 850 - Restomod
'67 Enfield 750 (TT7) - Resto

Offline jaguar

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Re: what would/did you build on a semi budget?
« Reply #5 on: March 15, 2011, 02:33:45 pm »
thats and interesting build...i like it.
yes i should have stated that the chains and guides would be checked and replaced.

never heard of using 360 pistons.  thought i read that back in the day guys used 350 pistons or something
do you have more info about that?  is this a "bolt" in kind of thing with 750 pins?

F3 cam?  i assume you mean the CB750F cam?
why is that?

you would cryo your rods over shot peening them?



from what i read the bottle neck of these engines is the head.  so more gains would be seen from opening up the head?

Offline wrenchmuch

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Offline jaguar

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Re: what would/did you build on a semi budget?
« Reply #7 on: March 15, 2011, 02:47:41 pm »
added it to my watch list.
thanks




i looked around and it seems that the 1 over cb350 rings are NLA.....
anyone have info on the use of twins pistons in a 750?

i love the idea of OEM+ motor building....

Offline MidnightLamp

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Re: what would/did you build on a semi budget?
« Reply #8 on: March 15, 2011, 03:57:43 pm »
3rd over CB350T was what I meant =P. My understanding (from seeing a set used first hand) is that the CB350 (twin) pistons are 64mm bore, and have combustion chambers compatible with a stock CB750. 3rd over (0.75) takes you to 64.75mm, which is a negligible amount smaller than a 836kit.

I'd take a set of cyclex pistons over those any day though...because they're $210 for a set and have the nice 10 1/4: 1 CR.

As for the F3 cam, I mean from the 77/78 CB750 F, the one with the bigger heads. I have the two cams in front of me, and the F cam looks nice and aggressive! This would need to be clay checked though, as always when running cams and pistons that aren't designed for each other...you never know if your head has been resurfaced at some point...

I wouldn't shot peen rods, based only on bad experiences with most shot peeing shops (they're far and few inbetween, and by the time you ship a set of rods to someone competent, get the work done, and shipped back you've already justified one third the cost of new rods. The bolts also add about a 3rd...factor in that your time is worth something and you're already over). In the hands of a competent person, shot peening can do wonders for fatigue strength, but under the wrong hands, it's just a pain that'll likely weaken your rods and cost you (due to deformation and stretching of rods).

I am, however, not a professional engine builder, or anything of the sort. I just tinker a LOT.

'75 CB750 - Racer
'69 CB350 - Racer
'68 Enfield 350/440(flat top) - Steet
'54 Enfield 350 - Resto
'74 Commando 850 - Restomod
'67 Enfield 750 (TT7) - Resto

Offline mlinder

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Re: what would/did you build on a semi budget?
« Reply #9 on: March 15, 2011, 04:15:48 pm »
The 350 pistons are, so far as I know, not a direct replacement. Shoulder work and something else needs to be done. Not sure what.

Mike can get your rods peened well, at a reasonable price.

The k1 cam is a nice one.
No.


Offline jaguar

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Re: what would/did you build on a semi budget?
« Reply #10 on: March 15, 2011, 07:23:28 pm »
what about staying with a stock bore and helping things rev and breath better?

is it worth it to lighten the crank and other components?
what would port matching run $ wise?

 

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