GS1327 Bigbore project

[Guest]

so where is the 'door'?

Assuming a 1327 with appropriate head mods and correct size carbs what is the limiting factor/component?

Would a V&H exhaust be the door or limiting component in such a motor? Or would the valves/heads always be the choke point in modding a motor?

it seems like 40-42 size carbs would be enough to avoid being a choke point even with a raised rpm operating range.

At some point with raised operating range cams, a 1327 would be limited by even a V&H exhaust rather than a head with bigger valves and porting.

This hypothetical build would be street motor. Perhaps if its not a race motor there is no serious limiting component if the heads are done right and the carbs are sized right...

The door he is referring to is the valve size.

All parts must be set up to work together if one thing is out then it won't work as good as it should. That is why one engine builder might be able to get a little more power out of the same size and motor parts over the other builders . What is the best assembly of parts? Ask 100 engine builders and you will get 100 different answers.

I myself like a lot of head on a little piston for the street and a lot of head on a big piston for big Hp

 

[rapidray]

All the power comes from the head & the cams. 140 hp at the rear wheel is EASY with an 1170 that will be ride across country reliable. 150 with a 1229 & 160-170 with a 1327. I like bigger motors for everything. The torque is where the fun is!! I once built a 1385 motor for fun to see what JUST a big piston kit would do. It was an 82 1100E with NO headwork, stock cams degreed at 105/107, 36mm 1150 CV carbs with a Dynojet stage 3 kit, K&Ns & a V&H street pipe. It ran out of air at 8500 rpm but would try to rip your arms off from idle to 8500! It was a STUPID fun motor that I let just about everyone I knew ride at least once. Scared the CRAP out of most of them but EVERY single person that rode it had a smile you couldn't slap off of them!! TORQUE is about the best part of any big motor that is set up for STREET riding! Once you have pulled the trigger on a motor like that nothing else is ever the same! I am building a 1570 for the street now & can't wait to feel one this big. This one WILL be big valves, cams & porting but big motors need all of the extra air to really optimize the parts.
Ray.

 

[Ecklund]

The door he is referring to is the valve size.

All parts must be set up to work together if one thing is out then it won't work as good as it should. That is why one engine builder might be able to get a little more power out of the same size and motor parts over the other builders . What is the best assembly of parts? Ask 100 engine builders and you will get 100 different answers.

I myself like a lot of head on a little piston for the street and a lot of head on a big piston for big Hp

Sounds right.

But what I was referring to was determining choke points, or doors, in the entire system.

For example if the 'door' were fixed in the 1327 by installing larger valves and porting the head and adding appropriate sized carbs would a V&H exhaust become the choke point or door?

This example assumes a cam with a moderately higher operating rpm range.

Another way to look at it; is the cost of the 1327, valves, porting, cams and carbs worth it if the exhaust can't flow enough to support the engine mods.

It seems that all these engine mods work well on motors up to 1233, but above that where is the choke point? The Exhaust?

 

[Ecklund]

What carbs will be used on the 1570?

And more interesting , what exhaust? Custom deal? V&H? Seems like most exhaust systems are designed to enhance minor mods. Is a V&H capable of fully supporting a 1327 or a 1570 for that matter.

I've seen the limited systems on eBay but don't know if they flow any better than a V&H.

A 1570 at even 9000 rpm must be trying to expel massive amounts of exhaust.

Seems like the choke points or doors in the head and carbs can be addressed; what about the exhaust?

 

[Guest]

What carbs will be used on the 1570?

And more interesting , what exhaust? Custom deal? V&H? Seems like most exhaust systems are designed to enhance minor mods. Is a V&H capable of fully supporting a 1327 or a 1570 for that matter.

I've seen the limited systems on eBay but don't know if they flow any better than a V&H.

A 1570 at even 9000 rpm must be trying to expel massive amounts of exhaust.

Seems like the choke points or doors in the head and carbs can be addressed; what about the exhaust?

Megatrons carbs

There are a few different systems you can use but most are for drag racing. It is very hard to find a good flowing street exhaust for the older bikes you almost have to put something together your self unless you go with a drag pipe. a old Murry Spider pipe is probably one of the best flowing pipes out there. I have carpenter header pipe with a Brocks megaphone and a home made mid pipe to make a nice up sweep exhaust that will flow like a drag pipe for a 1340cc 02 Bandit street bike. Sometimes you have to make your own systems also.

 

[rapidray]

What carbs will be used on the 1570?

And more interesting , what exhaust? Custom deal? V&H? Seems like most exhaust systems are designed to enhance minor mods. Is a V&H capable of fully supporting a 1327 or a 1570 for that matter.

I've seen the limited systems on eBay but don't know if they flow any better than a V&H.

A 1570 at even 9000 rpm must be trying to expel massive amounts of exhaust.

Seems like the choke points or doors in the head and carbs can be addressed; what about the exhaust?

41 mm Keihin FCRs, bored to 43mm. I have a V&H pro stock pipe that will flow plenty of air for an 11 to 1 compression motor. I will also use one of Paul Cashio's starters with 24 volts to it. Paul's starter will spin a 15 to 1, 1570 GS motor like a stock Busa motor!!

 

[Samsonite]

Ray.....Stop making me want to spend money!

 

[Rob S.]

Samsonite,

I don't notice a "cam crossover piece" on your top end oiler. Most bikes (pics) I see with top end oilers seem to have them. (Looking back to the beginning of thread; I love the looks of that wide-open exhaust. )

 

[rapidray]

I also have a BIG tube Bassani pipe that I could use but the bike will be too low for an under the motor exhaust. The good thing about the P/S pipes is that the collector is in front of the motor so it will only have a 2 & 1/2 inch pipe on the right side. I will be able to tuck it in tight & not lose as much right side turn clearance as I would lose with a sidewinder. Plus, no sidewinders have big enough primary tubes for this motor.
Ray.

 

[rapidray]

Ray.....Stop making me want to spend money!

But it really IS fun to build & ride stuff like this!! LOL!!!
Ray.

 

[Ecklund]

Thanks to both you and Ray for posting your experienced info.

So is there a top end limit with displacement for a common street pipe like the V&H? Seems to do OK with the 1170 and probably even the 1230.

For a street motor with head mods and proper carbs, would either of you recommend using the V&H street pipe for a 1260/1327 street motor?

I get the impression that the V&H pipe is used on 1260 and up engines not because it has adequate flow but because its cheap and commonly available.

Thoughts/comments?

 

[Samsonite]

Bike ran strong. But the engine is sounding like a sewing machine! Didn't mess with cam degreeing yet, set valves at .08" lash. Not sure what is going on. Tried re adjusting cam chain tensioner but to no avail. Cams looked good. Just getting loud tapping from top end. Should i set the valves tighter?

 

[blowerbike]

5 ish ain't bad.
8 is on the edge of being noisey IMO.

 

[rapidray]

Valve clearance should be .005 INCH.
Ray.

 

[Samsonite]

Sounds good. Could of sworn i was told 8 for aftermarket cams.

Thanks guys

 

[Samsonite]

Set the valves at 5 thousandths. Ticking still there. The whole top end is a rattling orchestra. Doesn't idle what so ever, but runs very strong at 2000+ RPM, absolutely screams. Does it sound like i may be off a tooth on cam timing?

 

[Rob S.]

Pictures! We must have more pictures!

And videos! With sound! We must have them.

 

[Samsonite]

Pictures! We must have more pictures!

And videos! With sound! We must have them.

I can't take pics or video until its worthy of pics or video!

 

[Rob S.]

You tell us it doesn't idle good but screams above, and I'm thinking '69 302 Z28.

Seems very worthy of pics and sound video.

We must have them. We must!

 

[Samsonite]

I was off a tooth on the intake cam

No more tapping.......
:dancing::dancing: