GT380 - Centre downpipe cooler than the outers
Posted: Sat Oct 02, 2021 4:39 am
Hi guys and thanks for letting me join this fantastic community. I have recently bought a 1974 US Suzuki GT380 that was imported into the UK a number of years ago and then registered in the UK on an ‘M’ plate.
It’s no show pony but is in decent condition for its age with almost everything but the tyres looking original or at least NOS.
I went for a 3-cyl 2 stroke triple as part of my retirement present as its just about the only inline engine format I have never owned, up to and including a CBX six in the mid 80’s. Just missing something with a V config…. maybe next one eh.
I live between Durham and Sunderland but originally made in Hull and have been riding bikes since I was 13 ish with C50’s & Raleigh Runabouts as track-bikes, then starting life on a FS1E once I was able to hit the road legally.
All this bike stuff got me into anything mechanical and I did my apprenticeship as a maintenance fitter then progressing to mechanical & process engineering specialising in high-speed production lines for personal care products over the decades.
My current bike is a 2017 Kawasaki Z1000SX that my wife and I use for bi-annual European tours and the odd world endurance race in France. Currently spending the early days of my retirement planning 2022's 3 week trip starting from Santander and ending in Amsterdam.
Anyway, that’s me…… Now for the Suzi!
I’ve had a good look thru the forum and have been unable to find the answer I’m looking for so starting my first thread and hopefully getting some feedback. I have a feeling it won’t be my last thread.
The bike fires up first or second kick everytime so that’s a good start eh! It runs OK if a little sluggish and smokes heavily when first started, however the smoke does usually clear after a decent run out. Oil pump timing mark looks synchro’d with the carb slide indicator, so exhaust draining & cleaning is part of the jobs to do list.
Anyway, the question I have relates to the centre pot / exhaust. The middle downpipe does not heat up anywhere near as quick as the two outer cylinders. After 30 seconds or so, it’s still possible to ‘dab touch’ the downpipe whereas the two outers would be melting skin.
Is this normal? Does anyone else have the same symptom / problem… or is it natural due to the centre pot exhaust gases being divided into two outlets and possibly more free flowing. I guess I don’t know for sure if I have a problem or not. Over time, the centre downpipe does become too hot to touch as you’d expect.
I’ve removed the plugs, cleaned and checked gaps etc. They were pretty clean, no hint of oil fouling and a decent colour. I swapped the plugs around to see if the problem shifted and it didn’t. I also swapped the condensers later to try and shift the problem…. If I have one. Again, the centre downpipe remained much cooler.
I’ve a few more things to try on the ignition side before venturing into fuelling but before I stop doing the easier stuff, I wanted to get some feedback if this is just normal or not.
Thanks for taking the time to read and hopefully feedback.
Cheers
Pete
It’s no show pony but is in decent condition for its age with almost everything but the tyres looking original or at least NOS.
I went for a 3-cyl 2 stroke triple as part of my retirement present as its just about the only inline engine format I have never owned, up to and including a CBX six in the mid 80’s. Just missing something with a V config…. maybe next one eh.
I live between Durham and Sunderland but originally made in Hull and have been riding bikes since I was 13 ish with C50’s & Raleigh Runabouts as track-bikes, then starting life on a FS1E once I was able to hit the road legally.
All this bike stuff got me into anything mechanical and I did my apprenticeship as a maintenance fitter then progressing to mechanical & process engineering specialising in high-speed production lines for personal care products over the decades.
My current bike is a 2017 Kawasaki Z1000SX that my wife and I use for bi-annual European tours and the odd world endurance race in France. Currently spending the early days of my retirement planning 2022's 3 week trip starting from Santander and ending in Amsterdam.
Anyway, that’s me…… Now for the Suzi!
I’ve had a good look thru the forum and have been unable to find the answer I’m looking for so starting my first thread and hopefully getting some feedback. I have a feeling it won’t be my last thread.
The bike fires up first or second kick everytime so that’s a good start eh! It runs OK if a little sluggish and smokes heavily when first started, however the smoke does usually clear after a decent run out. Oil pump timing mark looks synchro’d with the carb slide indicator, so exhaust draining & cleaning is part of the jobs to do list.
Anyway, the question I have relates to the centre pot / exhaust. The middle downpipe does not heat up anywhere near as quick as the two outer cylinders. After 30 seconds or so, it’s still possible to ‘dab touch’ the downpipe whereas the two outers would be melting skin.
Is this normal? Does anyone else have the same symptom / problem… or is it natural due to the centre pot exhaust gases being divided into two outlets and possibly more free flowing. I guess I don’t know for sure if I have a problem or not. Over time, the centre downpipe does become too hot to touch as you’d expect.
I’ve removed the plugs, cleaned and checked gaps etc. They were pretty clean, no hint of oil fouling and a decent colour. I swapped the plugs around to see if the problem shifted and it didn’t. I also swapped the condensers later to try and shift the problem…. If I have one. Again, the centre downpipe remained much cooler.
I’ve a few more things to try on the ignition side before venturing into fuelling but before I stop doing the easier stuff, I wanted to get some feedback if this is just normal or not.
Thanks for taking the time to read and hopefully feedback.
Cheers
Pete