EFE Starter keeps shearing bolts

[RevinKevin]

I have rebuilt the starter on a 1984 1100efe twice now,first time used bolts from local tool and bolt shop, they lasted very short time. Then rebuilt again ( both times had to take the starter clutch to engineers to remove sheared of bolts) only this time I used genuine Suzuki bolts as well as new springs & pins. All put back together with correct torque settings and thread lock. This time it  lasted about two months, bike is daily ride. Anyone know why this is happening. I had owned an 86 model before for 13 years aa a daily ride and never once had this issue. 

[Gixer1460]

Does it start on the button or take a few cranks? It's usually slow cranking or crank inertia kick back - they are quite fragile HT bolts as std. I eventually gave up after breaking allsorts of metal types - I serviced the s. clutch, springs, rollers and pins and MIG welded 3No 1/2" stitch welds from clutch to rotor - never broke again (using high comp and 24v starting!)

[Arttu]

That's pretty usual fault. Happening on almost every engine sooner or later, I think. If it isn't some big bore high compression engine welding shouldn't be necessary. Here are tricks that I have been using with good success:

• Use 12.9 hardness bolts. Possibly torque them a bit over Suzuki spec.
• Make sure that mating surfaces on the rotor, startes clutch and copper plate between them are clean and smooth.
• On EFE engine there should be a dovel pin between the rotor and clutch to take the load off from the bolts. However, the design is apparently screwed up. The pin is too short for the holes and it can slide down to rotor/clutch so that it doesn't make any contact to other side. Stuffing something in bottom of the hole should fix this.

[RevinKevin]

3 hours ago, Arttu said:

That's pretty usual fault. Happening on almost every engine sooner or later, I think. If it isn't some big bore high compression engine welding shouldn't be necessary. Here are tricks that I have been using with good success:

• Use 12.9 hardness bolts. Possibly torque them a bit over Suzuki spec.
• Make sure that mating surfaces on the rotor, startes clutch and copper plate between them are clean and smooth.
• On EFE engine there should be a dovel pin between the rotor and clutch to take the load off from the bolts. However, the design is apparently screwed up. The pin is too short for the holes and it can slide down to rotor/clutch so that it doesn't make any contact to other side. Stuffing something in bottom of the hole should fix this.

Thanks, no its not big bore etc ,all standard. Will strip down again and double ,triple check surface conditions. I did notice that pin seemed too short to be effective. Will source stronger bolts. 

[RevinKevin]

8 hours ago, Gixer1460 said:

Does it start on the button or take a few cranks? It's usually slow cranking or crank inertia kick back - they are quite fragile HT bolts as std. I eventually gave up after breaking allsorts of metal types - I serviced the s. clutch, springs, rollers and pins and MIG welded 3No 1/2" stitch welds from clutch to rotor - never broke again (using high comp and 24v starting!)

Thanks,bike is standard,will weld as last resort but I reckon there is some minor simple issue that is causing this problem

[Screwriverracing]

Lap the rotor to the shaft,  it helps.

Cheers SRR

[CockneyRick]

Advance the timing a little to try to cut the kickback happening  

There's a file somewhere giving details to sort it on GS/GSX's

[coombehouse]

On 10/22/2018 at 11:16 AM, CockneyRick said:

Advance the timing a little to try to cut the kickback happening  

There's a file somewhere giving details to sort it on GS/GSX's

Think you mean retarding the timing. Advance will make it kick back more

[Swiss Toni]

Sort the locating peg out with a ball bearing down the hole. That will take some of the load off the bolts. All the above mods will help too!

[CockneyRick]

10 hours ago, coombehouse said:

Think you mean retarding the timing. Advance will make it kick back more

I live in an alternative universe 

[nopokewithoutsmoke]

Thinking out loud...but would it help to wire up the starter and ignition separately? Is this easy or practical to do?

[Gixer1460]

Not out of the question - not hard to do, mainly used with high comp motors but should work as well with regular types. Or turbo it - nice low comp then 

[nlovien]

10 hours ago, nopokewithoutsmoke said:

Thinking out loud...but would it help to wire up the starter and ignition separately? Is this easy or practical to do?

believe an ignitech ignition can be programmed to do this - i.e. you spin the motor 1st with no ignition then trigger it as the engine is turning - you can obviously achieve this by flicking the kill switch after you start spinnig - well known technique to help a weak starter drive in another type of engine

note of using HT bolts: don't recommend over torque - they are more fussy than std bolts - over torque HT bolts and they are more prone to shear - seen it happen

[matt]

Once I sorted out the dowel on mine, the starter clutch has been fine, even with the standard Suzuki bolts.

I have just fitted an Ignitech unit, you can set up how many times the engine turns over before it fires, I've got it set to 4 and it has stopped the engine from kicking back.

[Arttu]

22 hours ago, nlovien said:

note of using HT bolts: don't recommend over torque - they are more fussy than std bolts - over torque HT bolts and they are more prone to shear - seen it happen

Care to clarify this a bit? Do you mean that a 12.9 bolt shouldn't be torqued higher than a standard 8.8 bolt? Or that a 12.9 bolt shouldn't be torqued over specification of a 12.9 bolt?

I agree with latter but first statement is simply wrong. Generally higher strength bolt material allows higher torque. See for example here: http://www.wtools.com.tw/STANDARD-BOLT-TIGHTENING-TORQUE.shtml

So maximum recommended torque of M8 bolt is 25Nm for 8.8 and 42Nm for 12.9. And Suzuki spec for starter clutch bolts is 23-28Nm. So my point was that if you use 12.9 bolts you can pretty safely torque them to for example 35Nm which provides more clamping between the starter clutch and rotor.  

[nlovien]

spot on - the latter - you can get away with a bit of +/- on the lower tensile - more ductile bolts but the HT you should be more accurate and set to the prescribed torque due to being more prone to crack failure 

[Gixer1460]

2 hours ago, nlovien said:

spot on - the latter - you can get away with a bit of +/- on the lower tensile - more ductile bolts but the HT you should be more accurate and set to the prescribed torque due to being more prone to crack failure 

That still doesn't make any sense! Yes lower tensile bolts can be +/- (why anyone would not tighten to prescribed torque is strange!) but they will stretch the more torque that is applied actually reducing the applied clamping force - great addage - 'More is often Less'. If the stock bolts were changed for, say 12.9HT bolts, a higher (above std spec.) can be applied and still be within their own quoted yield stress and as they stretch less, that pressure goes into the clamping force.

[nlovien]

  - i'm not referring to the actual torque value - just to the precaution when using HT bolts to be more focussed on not exceeding the recommended torque because of the method of failure - a precaution for anyone who may not be aware of this 

another one with HT bolts when the load is across the bolt - try to get a short shanked bolt versus a full threaded one such that the shank is across where the load is - less prone to crack fail across a shank versus a threaded part

 

Edited October 29, 2018 by nlovien

[Wolf]

Torque on bolts can drive you nuts .

 

[RevinKevin]

Hi Everyone,

                      thank you all for your comments ,tips,and advice . Sorry for the delay in my reply. The bike belongs to my son and he has been riding it as his daily ride since we fixed the starter problem. We had the snapped off bolts removed at an engineers, also had them give the surface of starter clutch  and  flywheel a minimal grind and  clean up. On reassembly we gave the brass plate a real good polish too. We cleaned/dressed  the dowel  and ran a drill down the dowel  hole and packed it  a little with  two pack plastic/metal compound so that the dowel gave enough meat to locate both flywheel and starter clutch. We used standard Suzuki bolts with locite and standard torque  settings. All ha s been good now for 3 months . My conclusion  is the dowel not being long enough to begin with. Thanks again for all your help and support guys.

[no class]

good to hear you are up and running !  I always hated that weak point of the efe ……