Toro Twister 1600 Utility Vehicle, B & S Engine

S

Skippydiesel

Well-Known Member
My neighbour has asked me to bring his very old Twister back to life. This I have done.

Powered by;
  • B & S V Twin, Horizontal Shaft, Model: 305447, Type: 0116-B1, Code:11030711 (made in Japan)
BUT!

I cant get the the engine to, no load, idle at the required 1025 +/_50 RPM. If I go that low it just stalls on me.

NOTE: RPM to go that low to take the "load"/tension of the belt drive so that the transaxle can be engaged without a large jerk and more importantly, so that the transaxle can be disengaged. At present, have to turn engine off, to remove load, then Forward / Neutral / Reverse can be disengaged.

Please advise how to improve low speed idle????

Some history;
  • Delivered to me in very poor condition.
  • Has been worked on, before me, by a complete idiot - lots of signs
  • Almost no, very black oil, showing on dip stick
  • Air filter almost completely blocked
  • Starter motor not operating
  • Battery charging circuit not connected - owner just charged up battery when engine not starting
  • Very dirty - lots of chaff in cooling system
  • Missing cowling air inlet grill
  • Lots more
Symptoms & work done;
  • Engine will fast idle for a significant time (3 minutes) then die
  • Tends to die when "gear" selected. When restarted runs normally.
  • Good high rpm performance.
  • Signs of high oil consumption - exhaust a bit smoky
  • Took top of carby - all appeared normal (may be I should have done a full strip & clean?)
  • New NGK BCPR6ES spark plugs
  • Armature airgaps very wide & uneven (looked like done by eye) - returned to 0.25mm
  • Intake/Exhaust Valve Clarence's (also very wide) - returned to 0.13mm
  • Oil & filter change
  • Air & fuel filter replaced
  • New starter motor installed
  • Cowling & fly wheel removed to facilitate removal of heavy chaff/dust contamination
  • Fixed broken charge wire
  • Removed & flushed fuel tank
  • Replaced all fuel hose's
  • Replaced air inlet grill
😈
 
Hello S.,

From the description this sounds like it has been run a long time and not properly maintained. That means the rings are very worn and the valves are not sealing properly. No amount of "catch up" maintenance will get this engine back to top running condition.
 
Thanks Auto Doc's.

Both you & I have focused on the engine. I think this may be a mistake.

Since posting I have thoroughly cleaned the carburettor. There has been some improvement in reliable slow speed/rpm however the problem with the drive belt not disengaging at low engine speed continues.

I have done some further investigation - I now think the problem is the engine driven centrifugal clutch/drive.

It appears that when worn, the clutch may continue to operate at a low engine speed ie not disengage. In doing so it is loading (pressure) the transaxle gears, making changing from Forward - Neutral - Reverse impossible, while the engine is running. As soon as the engine is stopped, the pressure on the transaxle gears is removed and the gear selection becomes easy.

I would realy like to hear from someone who has experience with Constant Velocity (CV) transmissions.
😈
 
Skippydiesel said:
From the (non) avalanche of responses, can I take it that no one on this Forum has experince with CV Transmissions??? 😈
Click to expand...
Most of the experience with CV transmissions is limited to the guys that work on ATV and SXS. Which for the majority of lawnmower guys is beyond their scope. It has been my experience with CV clutches that they either work or they don't and one that is not working correctly is easy to spot. with just a normal inspection of the components. They will get sticky, or noisy, or just sloppy in their operation.

Can't get engine to the required 1025 rpm which to me seems extremely low. I can see 1250-1450 but most don't even have the capacity to run the slow. What is the actual idle rpm that can be achieved.
 
Hi ILENGINE,
Sorry for the delay in answering - cant find my Tiny Tach.
Used a photo/ laser tach - best low idle I can get is about 1500 rpm. Even then it's likly to stall and engine speed not nice & even.

Given smelly exhaust (oil consumption?), uneven idle at not very low speed - I suspect it will need a top end overall - piston rings, possibly pistons and valve grind etc.

What think you?
 
Skippydiesel said:
Hi ILENGINE,
Sorry for the delay in answering - cant find my Tiny Tach.
Used a photo/ laser tach - best low idle I can get is about 1500 rpm. Even then it's likly to stall and engine speed not nice & even.

Given smelly exhaust (oil consumption?), uneven idle at not very low speed - I suspect it will need a top end overall - piston rings, possibly pistons and valve grind etc.

What think you?
Click to expand...
Briggs list idle speed on that engine at 1750, but could be modified by Toro. Good chance that the top end has a good amount of wear. But something to keep in mind is parts and labor can start eating toward the price of a new complete engine very quickly. Rings list at $47 US for each set. Pistons with the rings will run $92 each cylinder, gasket set. $102. And that is standard piston and rings. And I wouldn't be surprised if the cylinders are worn to the point of having a ridge at the top so probably needed at least .020 inch or .50mm oversize so now you add the cost of boring which for my area will set you back around $400 for 2 cylinders. Throw in the labor for R and R and overhaul and you bought a new engine. New engine list for $1400
 
ILENGINE said:
Briggs list idle speed on that engine at 1750, but could be modified by Toro. Good chance that the top end has a good amount of wear. But something to keep in mind is parts and labor can start eating toward the price of a new complete engine very quickly. Rings list at $47 US for each set. Pistons with the rings will run $92 each cylinder, gasket set. $102. And that is standard piston and rings. And I wouldn't be surprised if the cylinders are worn to the point of having a ridge at the top so probably needed at least .020 inch or .50mm oversize so now you add the cost of boring which for my area will set you back around $400 for 2 cylinders. Throw in the labor for R and R and overhaul and you bought a new engine. New engine list for $1400
Click to expand...
Its not my call but will pass on your advice.

FYI - I am advised this is a "special" engine, developed by B&S for the Toro Twister.
It would seem to have an extended & taped crankshaft/PTO, to suit the drive clutch.
One engine supplier, I spoke to, said his company had replaced the crankshaft of a new motor, with one from a dud, as cost effective(???) solution to sourcing a complete new special engine. 😈
 
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