11-04-2019, 04:27 PM
Where do I start?
I have been rebuilding a 1990 SR42 that I have found out has a chequered past on this forum when in the ownership of GrahamSWTRF , basically he couldn’t get it started.
I like a challenge and having retired early in order to accomplish my dream of becoming ‘an old git in a shed’ surrounded by bikes and machinery I took on the challenge .... and the bike is stumping me as well now!
Things I have found that I initially thought would be the cause of the ‘non starting’
1. The coil for ignition was dead, this has been re-wound by West Country Windings.
2. Springs missing from air screws on Carbs – springs added and screws reset.
Having had the bike in bits I have checked everything I can. I have had the head off, valves are good, no holes in the piston, CCT seems to function fine. The one thing that I did notice was that when setting the cam timing I was unable to perfectly line up the marks with the face on the head, one either pulled down very slightly or up very slightly depending on which tooth I set in the cam chain. The cam chain is well within the tolerances given in the WS manual. I have reset the decomp lever.
On the ignition side the coil has been re-wound, the coils and pick up coil check out according to the WS manual. I have swapped CDI’s just in case. The spark I am seeing is not the best I have ever seen but is nice and white (both plugs). I have traced through all the cables and cleaned/re-terminated as necessary.
On the carbs I have had them apart, checked and cleaned them and set the float level with the ‘wet method’.
In trying to get the bike started (it turns over fine and the decomp lever clicks off) I have connected a dummy tank and fed the fuel directly to the carbs. I have sealed the vacuum hose. Is this correct?
So a couple of questions, first the obvious one ‘why won’t it start’?
Other questions, ‘what have I missed?’ & ‘does this motor run a lost spark?’ – this is a bit desperate but I’m just wondering if the timing can be 360 degrees out.
Sorry for the length of a ‘first post’ but as a Mod on another bike forum I know a bit of detail helps in diagnosing issues, perhaps not this much but when I get started ........!
Anyway here is my bike as it stands today
I have been rebuilding a 1990 SR42 that I have found out has a chequered past on this forum when in the ownership of GrahamSWTRF , basically he couldn’t get it started.
I like a challenge and having retired early in order to accomplish my dream of becoming ‘an old git in a shed’ surrounded by bikes and machinery I took on the challenge .... and the bike is stumping me as well now!
Things I have found that I initially thought would be the cause of the ‘non starting’
1. The coil for ignition was dead, this has been re-wound by West Country Windings.
2. Springs missing from air screws on Carbs – springs added and screws reset.
Having had the bike in bits I have checked everything I can. I have had the head off, valves are good, no holes in the piston, CCT seems to function fine. The one thing that I did notice was that when setting the cam timing I was unable to perfectly line up the marks with the face on the head, one either pulled down very slightly or up very slightly depending on which tooth I set in the cam chain. The cam chain is well within the tolerances given in the WS manual. I have reset the decomp lever.
On the ignition side the coil has been re-wound, the coils and pick up coil check out according to the WS manual. I have swapped CDI’s just in case. The spark I am seeing is not the best I have ever seen but is nice and white (both plugs). I have traced through all the cables and cleaned/re-terminated as necessary.
On the carbs I have had them apart, checked and cleaned them and set the float level with the ‘wet method’.
In trying to get the bike started (it turns over fine and the decomp lever clicks off) I have connected a dummy tank and fed the fuel directly to the carbs. I have sealed the vacuum hose. Is this correct?
So a couple of questions, first the obvious one ‘why won’t it start’?
Other questions, ‘what have I missed?’ & ‘does this motor run a lost spark?’ – this is a bit desperate but I’m just wondering if the timing can be 360 degrees out.
Sorry for the length of a ‘first post’ but as a Mod on another bike forum I know a bit of detail helps in diagnosing issues, perhaps not this much but when I get started ........!
Anyway here is my bike as it stands today