Bought my first motorcycle: 79' Suzuki GS425e

Well... I finally got a bike. I passed the MSF class a month or so ago and have been hunting through craigslist everyday. I bought a scooter at some point, but it only lasted about 2 weeks before I sold it in hopes to buy a motorcycle.

It's a 1979 Suzuki GS425e, and it's already got a handful of mods on it. I'd like to start where the previous owner left off and turn it into a decent cafe racer. From what I can tell, at some point somone pulled the engine and painted that along with the frame black. It's got a new exhaust, clubman bars, K&N filters, and other little things here and there.

I got a good deal on it, but it runs a little bit funny. With the choke on, it runs very well, with a slight hesitation between 2-3k RPMs... but as soon as i put the choke off, the bike idles smoothly, but it doesnt respond to the throttle at all.... so when in gear and rolling you can twist the hell out of it and it wont do anuything... but with the choke on, it'll take off like a bat out of hell. This is my first time messing with carbs so I've gotta do some homework and figure out how they work. If anyone has any ideas, by all means hit me with em.

Here's a few pics of the new bike:

looks super clean & wicked sharp

dig the mags, reminds me of the metal honeycombs I had on my bmx 20 yrs ago.

I've been looking hard for my own first bike, also a Zuk - DR350 to set up for dirt w/extra pair rims & tires for motard style commuting. like you I am carb challenged so can't offer help on your problem, sorry.

good luck, have fun and be safe!

Nice. I like the black, looks like a mean little guy :). It'd look even better with the fork sliders blacked out too. I'm going a similar route with my Nighthawk 650. I wish I could put clubman bars like that on mine but the tank's in the way. Those are some funky looking tires, are they really old or just made in a vintage style?

Nice score! Before tearing into the carbs, try dumping some denatured alcohol into the tank . I run about a pint in a gallon and 1/2 or so of gas. It smells funny but cleans the gummy gunk out of the carbs.

It sounds like what happened with my 77 Honda CB550F Super Sport (still have it!) when I added the individual K+N filters in place of the restrictive factory airbox, but kept the stock jets and exhaust. Too much air in, not enough fuel, plus a little bottleneck in the exhaust. You're probably running lean (bad, bad, lean = hot). You may need to re-jet the carbs and add a less restrictive muffler.

Your choke kind of mimics the original, more restrictive airbox and filter.

Yeah that's exactly what the previous owner did... they ditched the stock airbox for the individual K+Ns. How can I tell if its running lean or not? The mufflers are also very unrestrictive it seems... It's loud as hell. According to the guy I bought it from, the carbs were just cleaned out before the bike was put up for sale.

If I do need to rejet the carbs (I have no idea how to go about doing this... time to do some homework on that), how do I know what sized jets to use? Would i just buy a bunch of different sizes and go by trial and error? And how much of a pain in the ass is it to rejet a carb anyways?

thats a sweet bike. me want.

Yavuz wrote: Yeah that's exactly what the previous owner did... they ditched the stock airbox for the individual K+Ns. How can I tell if its running lean or not? The mufflers are also very unrestrictive it seems... It's loud as hell. According to the guy I bought it from, the carbs were just cleaned out before the bike was put up for sale. If I do need to rejet the carbs (I have no idea how to go about doing this... time to do some homework on that), how do I know what sized jets to use? Would i just buy a bunch of different sizes and go by trial and error? And how much of a pain in the ass is it to rejet a carb anyways?

If the exhaust has been opened up, too, then you ARE running lean. (That's really bad, remember?).

This probably isn't the "GRM Answer", but if you've never done it before and you don't have the tools to synchronize multiple carbs, you're probably better off paying a bike shop to rejet it for you.

Nice little bike! I used to have a '79 750e in the same color combination, I always thought it looked real sharp. You could have gummed up carbs, but if the previous owner put on K&Ns that may well be the problem. Bikes of that era were very sensitive to that change - based on my own experience and that of friends, I'd recommend converting it back to the stock airbox and filters, the K&Ns aren't worth the effort required to get the carbs calibrated to work with them.

reminds me to start fixing my gs650g..triple disks, shaft drive, and an oil leak standard on every model

Cool. I've got a GS450, and it has similar issues to yours - a funny hesitation, especially when cold, but that disappears when warm. It also hangs the idle at about 3k RPMS sometimes.

I tore into it, cleaned the carbs, replaced the carb intake boots and intake boot O-rings, and it seems to have taken care of the problem. People with those K&N pods do report having to rejet the carbs - I suspect that's your problem.

Good luck, and head over to the GSResource forums for some helpful advice.

Oh, and stock airbox would be a great solution to this problem. Not that synchronizing 2 carbs is that hard anyway.