When is it time to do the top end?
Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan
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Craig380
- Expert racer
- Posts: 1254
- Joined: Mon Dec 01, 2008 2:52 am
- Location: Manchester, UK
Re: When is it time to do the top end?
Hard to say, really, until you lift the head and see if there's a noticeable wear 'lip' at the top of the cylinder on the exhaust side ...
1976 GT380 - wounded by me, and sold on
2006 SV650S - killed by a patch of diesel and a kerb in Feb 2019
2017 SV650 AL7 - naked and unashamed
2006 SV650S - killed by a patch of diesel and a kerb in Feb 2019
2017 SV650 AL7 - naked and unashamed
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JFISHSOLEVIBE
- On the main road
- Posts: 102
- Joined: Mon May 09, 2011 10:06 am
- Country: USA
- Suzuki 2-Strokes: 1972 GT380, 1972 and 1969 Honda CB175
- Location: Pittsburgh, PA.
Re: When is it time to do the top end?
Gotcha! Guess that's an easy way to see if that bore is worn.
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JFISHSOLEVIBE
- On the main road
- Posts: 102
- Joined: Mon May 09, 2011 10:06 am
- Country: USA
- Suzuki 2-Strokes: 1972 GT380, 1972 and 1969 Honda CB175
- Location: Pittsburgh, PA.
Re: When is it time to do the top end?
Okay so I've got an update!
Re-ringed the old 380 with standard size Suzuki rings after noting that the interior of the cylinders were in great shape. In fact, they still clearly showed the hone that was performed 6000 miles back when I did the rod end and rings. There was no piston skirt scarring or cylinder ridge... So I took this as a good sign.
Slapped it all back together and crossed my fingers and boom!
Sounds like a new motorcycles. Much more 2 stroke crackle that has me excited to finally mount of my chambers. Since the rings are brand new I took it easy on the bike, however I did gracefully take it up to speed (kept it under 5k) and it showed a marked increase in power. The broad powerband is back and the bike is revving with ease again.
Still not an equal pressure pulse from L and R cylinders but as this point I'd bet a $20 that the right pipe is full of junk. Chambers here I come!
Re-ringed the old 380 with standard size Suzuki rings after noting that the interior of the cylinders were in great shape. In fact, they still clearly showed the hone that was performed 6000 miles back when I did the rod end and rings. There was no piston skirt scarring or cylinder ridge... So I took this as a good sign.
Slapped it all back together and crossed my fingers and boom!
Sounds like a new motorcycles. Much more 2 stroke crackle that has me excited to finally mount of my chambers. Since the rings are brand new I took it easy on the bike, however I did gracefully take it up to speed (kept it under 5k) and it showed a marked increase in power. The broad powerband is back and the bike is revving with ease again.
Still not an equal pressure pulse from L and R cylinders but as this point I'd bet a $20 that the right pipe is full of junk. Chambers here I come!
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Craig380
- Expert racer
- Posts: 1254
- Joined: Mon Dec 01, 2008 2:52 am
- Location: Manchester, UK
Re: When is it time to do the top end?
Sounds good -- glad it was the easy fix option 
Did you check the size of the ring gap in the old rings, out of interest?
Did you check the size of the ring gap in the old rings, out of interest?
1976 GT380 - wounded by me, and sold on
2006 SV650S - killed by a patch of diesel and a kerb in Feb 2019
2017 SV650 AL7 - naked and unashamed
2006 SV650S - killed by a patch of diesel and a kerb in Feb 2019
2017 SV650 AL7 - naked and unashamed
-
JFISHSOLEVIBE
- On the main road
- Posts: 102
- Joined: Mon May 09, 2011 10:06 am
- Country: USA
- Suzuki 2-Strokes: 1972 GT380, 1972 and 1969 Honda CB175
- Location: Pittsburgh, PA.
Re: When is it time to do the top end?
I actually didn't even bother. I took one of the old rings up next to a new one and the difference in size was visible. I suspect next time I do this the overbore and once over rings and pistons will be a must. Thinking about changing two stroke oils this time though, perhaps to get a different result on wear.
