GS450 Rebuild

[sam000lee]

I've had my GS450 for a few years now and recently found another with 4,500 miles for $200 that had been in a mild accident. So I'm swapping out the engines and anything from the other bike that is in better condition then mine. Here's some before pictures the black one is the one I just picked up. It's funny but I think the thing that I'm most excited about the new bike is the original tool kit that came with it which I think is really cool. I'm not really going for a cafe or bobber thing but aesthetically I am into the whole minimalist/raw look.

What I'm thinking about doing:
- Cleaning everything up
- Top end rebuild (have to switch some parts out anyway)
- New mufflers (both of my right exhausts are messed up)
- Pods (I know - but I'll have to rejet anyway due to ^^^ so figured if I was ever going to do it nows the time)
- Make a new seat - my old one was in bad shape and my new one is in awesome shape so I think first I'll try shaving down the old one and putting a new cover for a less bulky seat.
- Fix wiring - My wiring has a lot of temporary measures so that I could ride for the summer after putting in a polaris R/R but is in desperate need of cleaning up.

[sam000lee]

First question: Theres two exhaust studs stuck in my old head and an intake screw broken in the new one. After I botched drilling it out (drill bit snapped in the screw aghhh) I bought another head from ebay. The valves have a lot of deposit on the ebay head vs the lovely clean ones on my new engine but I've heard that due to wear patterns, etc. maybe its not such a good idea to swap valves between engines. Is it better to clean the valves on the head or switch them out? Tips for doing so would be appreciated.

Also, I bought a cheapo gasket set and the piston holes for the pistons are a slightly different shape - think it matters? The old gasket seems to be in great shape would it be awful to just reuse it?

Valves in Ebay head:


Valves in my new engine

How the new gasket sits in on the cylinder


It's 60 degrees here in MA and so the weathers perfect for the "winter" project

[Rensdw]

don't swap the valves!

IMHO it's best to have the original head repaired by someone who can get it done.
The head gasket gets crushed so reusing it is not the way to go, it might work, it might not.

If you are going to use pods the put an extension between the pod and carb, a simple plastic pipe will work, at least 2 inches long, the longer the better.
This will calm the airflow down because pods will mess it up, and will help the vacuum signal in the CV carbs, this will help to get a consistent tune.
If you don't do it for the looks then I suggest to keep the airbox.

[pete]

My 2 cents... don't use cheap gaskets! I did that on mine and have now replaced nearly every single one with a genuine gasket. They go brittle real soon and don't keep the oil in which defeats the whole purpose.

And after my experience with good quality K&N pods, cheapo pods, and now velocity stacks, I say go velocity stacks any day but with foam filters over the top. The throttle response is smoothest when using the stacks by far and that makes it so much easier to get your fueling at least close to right.

[sam000lee]

2 into 1 air intake?

Has anybody on here tried/heard of a 2 into 1 air intake? I just read through this thread on an xs400 forum discussing switching to a one-carb. setup, but havn't seen anybody do the same for just the air intake. The possible advantage would be that it would be more restrictive, countering the less restrictive filter that would be at the end, but then the carbs would be competing for air so it might end up being too restrictive.

[pete]

I've never had experience with it but every thread I have read about it says less performance. Of course it does simplify things such as no need for carb balancing but for my money if it's less performance/more restrictive I'll pass. I need all the little ponies I can squeeze out of my 450

[tkent02]

The reason motorcycles have one carb per cylinder is for performance. Not sure how much difference it would make but even econo bikes have one carb or one throttle body per cylinder so it must be a fairly large amount.

Reuse the head gasket, only temporary for test purposes, I have done it a couple times to test run an engine, to see if a transmission was good before modifying an engine or whatever. Also once just slapped a 1000 together to sell to someone who needed a cheap bike quickly, he knew it would leak bout he didn't want to spend the money for a new head gasket at the moment. They all leaked a little right away. Use Suzuki gaskets for anything that's hard to get to like head or base gaskets.

As long as you are in there, consider GS500 cylinders and pistons. They are cheap, a ten percent bump in displacement, and it just bolts right on. Get the 500 cam chain tensioner with the cylinder, the 450 one won't fit. Same with the head gasket and base gasket. I think I paid something like $50 for the whole set, maybe another $35 or so for the 500 head gasket. Use the 450 cylinder head.

Well worth it, but I'm riding at 6'000' elevation so everything has a bit less power anyway.

[John Park]

Has anybody on here tried/heard of a 2 into 1 air intake? I just read through this thread on an xs400 forum discussing switching to a one-carb. setup, but havn't seen anybody do the same for just the air intake. The possible advantage would be that it would be more restrictive, countering the less restrictive filter that would be at the end, but then the carbs would be competing for air so it might end up being too restrictive.

I think the XS 400 is a 360 degree crank; that means the thing has a half turn of the crank between intake strokes. A GS twin has one intake stroke followed by another and then two strokes of rest. So the cylinders aren't being treated equally unless they each have their own carb. One gets first crack and the other takes seconds. Single carbs were common on old British twins, but they were all 360 degrees.

The stock air box is a 2 into 1, or 1 into 2 actually, and that's a good reason to make it big to overcome the 180 degree firing order, which they did. Hard to beat it with pods or whatever.

The head gasket you have looks to be for a GSX 400 4 valve motor, common outside the USA. That has a 67mm bore while a 450 is 71mm. Get a new OEM 450 gasket; you will eventually. Don't even think about using silicone or whatever on the old one.

I wouldn't worry about the deposits; just scrape them off. What I would do is to install your cams in the head and rotate them [vice grips] so the valves are open and inspect the seats and faces. I've found that the seats tend to corrode and pit over time. If they look way uglier than the ones on your old head, I'd consider pulling the valves out and at least lapping them in.

The other thing to do is to fix the 'old' head. Get a welder to weld a nut to the top of the broken off bolt[s] and the heat will almost always make them easy to unscrew. If they're broken off well below the surface it's more of a challenge.

[sam000lee]

Updates: Seat

Havn't updated this in a bit. I'm waiting on a couple of valve shims before I put the engine back in. Right now I have the 'new' engine with the ebay head on. Thinking about putting a gs500 cylinder in the other one, per tkents suggestion, but that's after I get this up and running. I've ordered some emgo shorty mufflers, too, and am going to try to get the jetting right with pods (but don't worry I have two intact airboxes if things aren't working out).

I'm currently working on my seat. I shaved down the old one where the cover was falling apart and am making a new cover out of 8oz veg. tanned leather. I think this thickness/quality of leather will be really comfortable as it will mold to my butt over time. In the process of wet-molding it to shape and then I'm going to hand stitch it together after embossing the top panel (similar to how the stock seat looks) and then will dye it. Still deciding on colors so let me know what you think. Can't go wrong with black, but was thinking of a "British saddle" color which is basically brown with a red hue to it. I thought that might look good with the side pouch I made to replace the missing side cover.

If the pods work out, I'm going to move the electronics panel into the frame a little bit so I can make a matching leather side pouch for the left side and get ride of the plastic cover.

I'll post more pictures of the seat when its done.

Shaved seat:


Starting to mold the rear:

A little more:


Some more:


Side pieces:

[pete]

Good stuff, thanks for showing the progress of the seat as I've never really looked into it before. I wouldn't mind being able to re-cover my own seats so it'll be good to see how it's done to see if it's something I'm capable of.

At some point I need to redo the 450 seat as a solo seat and I'll need to do the Kat seat for the same reason... getting them done professionally ain't cheap here!

[sam000lee]

Things are coming along slowly for me, but aren't at a dead stop. Pete - I don't think this is the typical way people redo their seat covers! Normally its with MUCH thinner leather and is sewn by machine. I make leather bags (see side pouch in the pictures!) and am used to hand stitching this thick stuff. I am regretting it since its taking a long time, and since I started wish that I had gone from scratch and done a fiberglass seat pan but it's still a fun project for me. That being said, I am really interested to see if it makes the seat more comfortable due to the thick leather.


Questions: Engine's back in the frame with valves shimmed and new gaskets - I got a pair of emgo shorty mufflers, and am going to be ordering these UNI pods from DCC as well as some other miscellaneous items (exhaust reducer, etc.).

1. Current jets are 115 mains and 17.5 pilots (I believe this is stock). As a starting point, I was thinking about going up to 120 mains (2 steps up, one for pods and one for exhaust) and 20 on the pilots, as well as shimming the needle by one notch. If I want to order a couple of extra jets now, so I don't have to keep paying for shipping, where is this likely to need more calibration, i.e. If maybe it's likely that I'll need to go up another size on the mains, I would also order a pair of 122.5 main jets.

2. Does anybody have experience with "OEM" vs. "OEM equivalent" jets. The "OEM equivalent" ones are slightly cheaper but obviously if they're not worth it I'll just get the regular "OEM" ones. I am looking at these jets from JETSRUS

[pete]

I'd be inclined to go with stacks rather than pods... from my experience the throttle is much smoother and it will be easier to tune. DCC has these, won't filter quite as well as the pods but you could always pop the filter off and get a foam filter over the top if that's a big concern:

http://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-carburetor-parts-lightweight-50mm-velocity-stack-12-6650.html

As for jets, I've only ever used genuine Mikuni so can't comment on the generic ones.

[sam000lee]

Rats I wish I had seen those earlier - for some reason I always assumed that velocity stacks were going to be a lot more expensive and the thought of dirt going in does worry me a little bit. Either way, I ordered the UNI's about an hour ago so I guess it's too late. I do plan, as Rensdw suggested, on putting an extension pipe in to calm the airflow.

Any comments on the estimates for the jet sizes?
(Also thanks Pete - I've gotten a lot out of your build thread and reading your comments for other GS450 threads!)

[pete]

All good, as long as there's no lip in those pods to interfere with air flow then that's a good start! An extension pipe in there should help for sure.

It's a bit tricky for me to comment on jet sizes due to running GS500 cam's and carbs on mine, but as a general rule pods and a free breathing pipe typically means 4 sizes up on the main, and expect to have to shim your needle to lift it as well.

Glad I can be of some help!

[sam000lee]

Been a while since I've updated this - been super busy with school/teaching. I've got things mostly back together and just need to properly sort out the wiring (I've been eyeing one of the vintage connections kits for about a month now and should probably just order it). Here's a picture of the almost finished seat - I think it came out pretty well!


I have a few days in the next week to work on it (even thought it's supposed to snow) so will post some more pictures soon.

I have one question for the time being: How much should the rear wheel spin in neutral after being given a shove? Theres a couple threads on this but they are all for bigger shafties, and answers seem to vary from 1/8 rotation to there should be little resistance.