My new 360, on a 180 course! Shortblock all buttoned up

[tobiism]

Well, I've always wanted one of these little Honda twins. I found a parts lot on that holiest of sites, Craigslist. Not a bad haul for $80!
The frame I've already cleaned up, stripped most brackets, and painted(gotta love that appliance enamel. I'm attacking this bike with gusto, trying to get it done fast. The engine I've got the top end off of to clean up and make au-natural. I'm going to do some valve pocket work, and maybe a 378cc conversion down the road(thanks to crazypj's posts about this conversion)
I'm super stoked about the megaphone 2-1 collector, I've never seen one like this before.

 

[boingk]

Re: My new 360, on a 180 course!

$80? Nice! Good start on it, as people say its always the attention to detail that makes these projects something else. As for the collector, that is different. I don't mind it at all. You may even be ablt to do something crazy and have both downpipes sweeiping under the engine completely, with the collector dead-centre and the megaphone sweeping to one side out from under the bike.

This'll be good to watch, good luck with the build - boingk

 

[tobiism]

Re: My new 360, on a 180 course!

I don't usually tear down engines on the the project bikes I buy, unless they show some reason for it. Something was bugging me about this engine, making me want to open it up.
What a good thing I did! This swarf was plugging the oil passage to the mainshaft. Its aluminum, and I'm not sure where it came from.

Everything else is looking in good shape, I just need to have the cylinders, head, valve cover, and cases blasted to get rid of the crappy paint job the P.O. laid down.

 

[gribbs]

Re: My new 360, on a 180 course!

Looks like you know what you are doin man, and good find on that burr. Keep more pics and info comin

 

[tobiism]

Re: My new 360, on a 180 course!

Looks like you know what you are doin man, and good find on that burr. Keep more pics and info comin

Thanks man.
I got the cases cleaned up tonight. Used one of those nylon bristle cups on my right angle die grinder.
They came out really nice.
I think I'm going to paint them with the Duplicolor High-heat paint, but I'm not sure what color.

 

[andycafe]

Re: My new 360, on a 180 course!

Dude i love a good bits pile, looking forward to checking out this build.. Andycafe..

 

[mysta2]

Re: My new 360, on a 180 course!

...I'm going to do some valve pocket work, and maybe a 378cc conversion down the road(thanks to crazypj's posts about this conversion)...

What what what!?

More info required (Search turned up only this post)

I'm in the middle of a 360 teardown right now and need as much tweaker info as I can get, I want to get everything out of this motor that it can give me.

... after some chasing all over the net:

http://www.totalmotorcycle.com/BBS/viewtopic.php?t=26650&postdays=0&postorder=asc&start=0&sid=7bfa2fef18305f3f4669b4225c78a23d

http://forums.sohc4.net/index.php?topic=30210.0

are those the posts of which you typed?

 

[tobiism]

Re: My new 360, on a 180 course!

Yup, thats it alright. GS850 pistons are a 2mm overbore, and are even lighter than the 360 pistons. I've yet to find a set, but will be sure to grab them when I do.
Megacycle also makes a cam for the 360. Thats on my shopping list as well.
I'm going to adapt over two mikuni c.v. flatslide 34mm GSXR water cooled carbs.
With a little higher compression, and a nice 2-1 exhaust, it should stomp pretty well!

What what what!?

More info required (Search turned up only this post)

I'm in the middle of a 360 teardown right now and need as much tweaker info as I can get, I want to get everything out of this motor that it can give me.

... after some chasing all over the net:

http://www.totalmotorcycle.com/BBS/viewtopic.php?t=26650&postdays=0&postorder=asc&start=0&sid=7bfa2fef18305f3f4669b4225c78a23d

http://forums.sohc4.net/index.php?topic=30210.0

are those the posts of which you typed?

 

[mysta2]

Re: My new 360, on a 180 course!

There are 8 on ebay right now, one set comes with the bores too though. I've got an e mail into the local breakers, to see if they can get a set. If that doesn't work out maybe we could split this set:

http://cgi.ebay.com/ebaymotors/Pistons-1979-Suzuki-GS850-GS-850_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116QQhashZitem3a48b02f0cQQitemZ250327609100QQptZMotorcyclesQ5fPartsQ5fAccessories

Looks like right now there are also two NOS ones just south of here, but that guy wants $40 each.

by water cooled carb you mean a carb of a watercooled bike right? Aren't all gixxers water cooled... otherwise I've never heard of a water cooled carb.

 

[tobiism]

Re: My new 360, on a 180 course!

I've been looking for new ones. I don't really want to go through the trouble of the conversion and use used pistons.
Yup, the carbs are off of a watercooled GSXR. GSXR's began as oil/aircooled(think Katana and Bandit) and then became watercooled in the mid-90's.

There are 8 on ebay right now, one set comes with the bores too though. I've got an e mail into the local breakers, to see if they can get a set. If that doesn't work out maybe we could split this set:

http://cgi.ebay.com/ebaymotors/Pistons-1979-Suzuki-GS850-GS-850_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116QQhashZitem3a48b02f0cQQitemZ250327609100QQptZMotorcyclesQ5fPartsQ5fAccessories

Looks like right now there are also two NOS ones just south of here, but that guy wants $40 each.

by water cooled carb you mean a carb of a watercooled bike right? Aren't all gixxers water cooled... otherwise I've never heard of a water cooled carb.

 

[tobiism]

Re: My new 360, on a 180 course!

Well, I painted my engine cases and cam cover tonight. I'm using Ford Grey Rustoleum engine enamel.
This weekend I'm going to borrow my friends sand blaster so I can clean the cylinders and cylinder head. Those crevices are too hard to get into with the paint stripper.

All of the hardware on the cam cover will be removed and polished, I totally forgot and painted right over them after prepping the cover!

 

[mysta2]

Re: My new 360, on a 180 course!

Just bought the 2 NOS pistons... hope I didn't overpay, don't really know what a 30 year old new piston is worth.

Engine looks good, looks military. What are you going to blast the rest of the motor with, and are you then going to paint it? or leave it raw?

 

[tobiism]

Re: My new 360, on a 180 course!

Thats cool you got the pistons. Thats not a bad price. But now you have to find the rings.
The rest of the engine will be sandblasted and painted to match, but all the covers will be polished, with the Honda logos done in red. Thanks!

 

[mysta2]

Re: My new 360, on a 180 course!

That's what Bikebandit's for:

http://www.bikebandit.com/suzuki-motorcycle-gs850gt-1980/o/m6122

...actually it looks like I may have been able to get the pistons there too, possibly cheaper.

 

[tobiism]

Re: My new 360, on a 180 course! (now with a little head porting)

alright, got the intake valves out so I could start cleaning up the bowl. Where the valve seats are pressed in you can benefit from cleaning up the transition area from seat to port. Basically you want a nice smooth(by smooth I mean no rough edges, not like polished smooth) transition from the steel of the seat to the aluminum of the port. I use a stone grinding bit and a 120 grit flapper wheel in my drill for this.
Here is one intake after doing all of the smoothing out on the bowl.

Okay these are pictures of the intake that I haven't done yet. You can see all of the sharp edges left behind from the maching process when the seats are installed.

Here is a look through the intake at the finished bowl area

unfinished bowl area.

This is something everyone should do. Its so easy and probably only took me a half hour.

 

[mysta2]

Re: My new 360, on a 180 course! Now with some minor headporting

Love it! we need more posts like this.

 

[Hot Rod Troy]

Re: My new 360, on a 180 course! Now with some minor headporting

Great posts. Keep 'em comin'.

 

[tweakedlogic]

Re: My new 360, on a 180 course! Now with some minor headporting

I port every head I take off. One thing you might have over looked is swirl. When the charge enters the cylinder, you want it to swirl or spin as it enters. It's kinda hard to do in these heads because they are a straight shot. All you have to is remove more material from one side than the other and ramp into the low side (head installed the low side is the one that had very little removed). If you want more swirl you can either add something like JB weld or you can TIG more material in. Most modern heads have this incorporated already.
That being said, you will still see volumetric gains with what you've done. Good job. Be sure not to waste it and get a 3 angle valve job. You can also cut or grind down the valve guide the the ceiling of the port. Don't worry, they are long enough to control float.

 

[tobiism]

Re: My new 360, on a 180 course! Now with some minor headporting

I port every head I take off. One thing you might have over looked is swirl. When the charge enters the cylinder, you want it to swirl or spin as it enters. It's kinda hard to do in these heads because they are a straight shot. All you have to is remove more material from one side than the other and ramp into the low side (head installed the low side is the one that had very little removed). If you want more swirl you can either add something like JB weld or you can TIG more material in. Most modern heads have this incorporated already.
That being said, you will still see volumetric gains with what you've done. Good job. Be sure not to waste it and get a 3 angle valve job. You can also cut or grind down the valve guide the the ceiling of the port. Don't worry, they are long enough to control float.

Hi, thanks for the info, it is appreciated. I've contemplated the valve guide work, and it will definitely get a good valve job. As far as the swirl you mentioned, I prefer not to get into any real material removal without a way to test for gains/losses.
Matt

 

[Swagger]

Re: My new 360, on a 180 course! Now with some minor headporting

As Mr. Tweaked says, shave those guide right down and blend to the port wall, you can get a good bet there.
You can stimulate the charge swirl effect a bit by grinding a shallow "trench" from one side of the valve guide to the opposite side of the valve seat. It's called laminar disruption or some such blather....it's been 15 years or so since I took that porting workshop....gimme a break. heh
By doing so, in essence that trench will break the smooth flow across the wall of the ports 'long side' and because air (and air/fuel) is technically slightly viscous, it will drag the flow in that direction. It's not as good as actually building up the portion but it's where the swirl porting movement came from. I've done that alone and gained a bit of power overall but really saw ridability improve across all the rpms.