Update: I borrowed coils from another motorcycle I have, and it definitely changed the way it runs. It still skips a beat every now and then on one of the cylinders, but nothing major. This leads me to believe that I have a bad wire or connector as Highpower pointed out. Further investigation will commence.
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Suzuki GR 650 Tempter problem
- Thread starter GuyRDag
- Start date
Aahh, so you are norwegian too ! Btw, my cousin has a Suzuki GR 650, but his is bone stock! And generally works fine, even if a little bit "too soft" for my taste.... The only problem I know of, is a blown voltage regulator/ rectifier. I am doing most of basic maintenance for him, oil changes/ tyres/ chain/ brake pads and fluid, etc.
Regarding the mufflers, I really doubt they are the stock ones. I can take some pics of stock ones and post later in the coming week.
I guess one could consider the GR650 as a sort of more evolved late model XS650 Special, with its DOHC and counterbalanced engine, single shock rear suspension, and the quite clever variable inertia crankshaft assembly (centrifugal clutch disconnects the external flywheel above 3 k rpm)
Regarding the mufflers, I really doubt they are the stock ones. I can take some pics of stock ones and post later in the coming week.
I guess one could consider the GR650 as a sort of more evolved late model XS650 Special, with its DOHC and counterbalanced engine, single shock rear suspension, and the quite clever variable inertia crankshaft assembly (centrifugal clutch disconnects the external flywheel above 3 k rpm)
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Aha! ArcticXS makes sense when being Norwegian! The GR 650 seems to be a well put together motorcycle and it is surprisingly quick and nimble (when it runs normal that is). The XS 650 has a much more appealing visual look than the GR 650 in my opinion, but there are not many for sale and the prices are quite steep. I found only one for sale in Norway right now and the price is 70.000 nok which would translate to around 7.000 USD. It is from 1971 which I guess means kickstart only? I will have to check the regulator/rectifier again as I used a digital multimeter to check the charging and the meter switches between AC and DC automatically. A picture of the stock mufflers would be much appreciated.
One thing to be aware of when it comes to the charging system, is that one of the 3 AC wires from the stator is wired through the headlight switch, effectively reducing the alternator output when headlight is off. Presumably to reduce the thermal load on the voltage regulator/ rectifier unit. In stock form, the GR has an automatic daylight driving light below the headlight, with a smaller bulb (most likely 21 W) The alternator gives enough power to run this driving light and ignition system with one leg disconnected by the headlight switch. (I.e running as a single phase alternator instead of three phase)
If you or the dreaded PO has wired the headlight to be powered from this driving light power, then your alternator output will be marginal at best, possibly causing ignition issues.
If you or the dreaded PO has wired the headlight to be powered from this driving light power, then your alternator output will be marginal at best, possibly causing ignition issues.
I also had a closer look at your carb/ air filter setup. It looks like VMs in the picture you posted. Correct?
In any case, the air filters do not look like genuine K&N filters, and are also quite small in my opinion. I have seen other filters like yours with an inside lip that are guaranteed to mess with the air flow...And also prevent proper operation of the stock CV carbs, as discussed in almost all carburation threads in this forum.
In any case, the air filters do not look like genuine K&N filters, and are also quite small in my opinion. I have seen other filters like yours with an inside lip that are guaranteed to mess with the air flow...And also prevent proper operation of the stock CV carbs, as discussed in almost all carburation threads in this forum.
This is very interesting. I had a similar problem with my 1972 Honda CB 350 twin. It also had one wire connected through the light switch. The charging output on that model was bad to begin with and it definitely didn’t help with the added “limp mode”. I remember there was a fix to remedy this “flaw”. Maybe the same can be done for the GR. Thank you very much for the input!
You're absolutely right — those filters are definitely not original K&N filters. I just put them together temporarily to check if the carburetors were causing the issues. After testing with a new pair of coils yesterday, it seems the main problem lies with the ignition system. Once that's resolved, I plan to reinstall the original CV carbs and, of course, use high-quality filters. You're very observant, and I really appreciate your input.
I just did a google search, and found a 1983 Cycle World test of the GR. It appears there was a "budget" version named GR650X, which had wire spoke wheels. On a cafe style build like yours, a spoked 18" rear and spoked 18 or 19" front would be the icing on the cake 
Surely, some US or UK breaker could have spoke wheels or hubs.....
Surely, some US or UK breaker could have spoke wheels or hubs.....
That is an excellent idea! I will google it laterI just did a google search, and found a 1983 Cycle World test of the GR. It appears there was a "budget" version named GR650X, which had wire spoke wheels. On a cafe style build like yours, a spoked 18" rear and spoked 18 or 19" front would be the icing on the cake
Surely, some US or UK breaker could have spoke wheels or hubs.....
A few years back, I bought a pretty nice 1973 Honda CB450 and at a good discount because it didn't run well. It started well, idled nicely but started to miss once you took the revs up a bit. I figured it'd be an easy fix.
When I got home, I checked all the usual stuff, points timing, Fuel system. No improvement. Then, I noticed the horn, below the tank wasn't fitted tightly, so I removed the tank and tightened the two bolts that held it AND THE COILS to the fame. Presto! She would rev to the moon.
Don't discount a ground issue.
When I got home, I checked all the usual stuff, points timing, Fuel system. No improvement. Then, I noticed the horn, below the tank wasn't fitted tightly, so I removed the tank and tightened the two bolts that held it AND THE COILS to the fame. Presto! She would rev to the moon.
Don't discount a ground issue.
Great story, and a great motorcycle! Sounds like you got a real bargain. I’ll definitely look into this. When I got the bike, it had been neglected and was covered in corrosion. Sometimes I feel like I’m the kind of person who buys cheap motorcycles, only to discover there was a very good reason the previous owner wanted to get rid of them
And remember the battery earth too. I know I've mentioned this before, but replacing the battery earth wire on my XS650 - it looked ok but must've had internal cracks - made more difference than you would think, bike runs better, revs better.
Good advice! I think I will put in a new cable just to be sure.
And you said you powder coated the frame. Make sure you clean the powder coating off the spots where the ground wires connect to the frame.
Will do! I'm going to check and recheck every cable and connection.
Thanks! They look similar, but definitely not the same. Hopefully this is not what's making it run poorly.
I took a closer look and can confirm that they are stainless steel mufflers from Motad. From what I’ve found online, Motad is a leading manufacturer of road-legal replacement exhaust systems for vintage Japanese motorcycles. And I painted them black...
Unfortunately, Motad is no more.I took a closer look and can confirm that they are stainless steel mufflers from Motad. From what I’ve found online, Motad is a leading manufacturer of road-legal replacement exhaust systems for vintage Japanese motorcycles. And I painted them black...
I have a Motad stainless system on the W800 and it gives a nice mellow note, big improvement over the original which sounded like a sewing machine. Plus it's much lighter and a lot easier to put on or take off - on the Kawasaki original system, the header pipe and silencer are one piece and don't come apart, plus you have to wrestle with a link pipe under the engine.
If they are stainless, and you regret the painting, you can just remove the paint, and sand/ polish to whatever finish you like!I took a closer look and can confirm that they are stainless steel mufflers from Motad. From what I’ve found online, Motad is a leading manufacturer of road-legal replacement exhaust systems for vintage Japanese motorcycles. And I painted them black...
