Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Laverda Dave on November 16, 2023, 04:51:54 PM
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The sump plug on the rat resto bike has been stripped at some point by the PO. He has attempted to fix it using a helicoil of a size unknown. A large, double headed, long hollow bolt that came out of a gas fitting has replaced the original sump bolt!
I know there have been various threads on stripped sump threads elsewhere but I cannot find them using the search bar :(
My question is: Can the original sump bolt thread be repaired? I know there is a big issue with the length of the thread in the sump pan itself as there is very little meat in the casting and Honda built up the area around the sump thread with two 'ears' (best way I can describe them) either side of the drain hole in order to allow the sump bolt thread to run further into the sump pan casting. These two 'ears' are still in place on my sump as in they haven't broken off.
So, can the existing helicoil be removed and can the sump drain hole be built up with weld and the thread re-cut, is this poosible and does anyone know of a company that can do this work?
If as I suspect the answer is negative, does anyone have a 400/4 sump they are willing to sell with the drain plug thread in good condition? There is one on ebay but having contacted the buyer FOUR times without any response I am loathe to buy it unless he can confirm the thread is in good condition.
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I suppose it will depend on the size of the helicoil. I have a sump plug repair kit that allows you to drill out the original thread, re-tap with supplied taps and then replace with an over size sump plug (again supplied in the kit) If you don't get anywhere near to you, happy to repair for the cost of postage back to you...
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I know where there is a NOS one but it's for the 350 four not the 400 four. Different part number so maybe of no use.
Fairly sure someone on here will have a spare somewhere.
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Dave,
I may have a sump, I'll have a look tomorrow.
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Thanks for the replies all.
Matt, I've never heard of a sump thread repair kit but sounds promising. I will try and determine the helicoil size tomorrow but I do know it's taken a fair bit of material off the boss, I will also try to determine the size of the weird replacement sump bolt. It may be salvageable and it's a shame the thread is stripped as the fins are perfect. Watch this space👍
Ken, Two Wheel Spares had a used 350 sump but they failed to respond when I asked them if it would fit a 400/4
The one on eBay is described as 350/400 sump but again the seller has not responded, eBay can be utterly useless sometimes!
Deano, thank you for the offer, If you do have one going spare and the sump thread is good that would be great. Visible condition not important as long as there is no fin damage. I will getting it vapour blasted along with the rest of the casings before painting.
Cheers All👍
Dave
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If the hollow bolt came from a gas fitting it could be BSP thread.
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Hi Dave.
Not great news, I have two spare sumps but both have issues. One has already had a thread repair to the sump plug thread, looks like it had been re-tapped with a larger thread and a brass reducer to take the original sump plug. The thread on the second one is ok but it has some minor fin damage.
If you don't get any joy elsewhere let me know if you want me to post any pics.
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After careful checking today I can confirm the bodged oil bolt is in fact a modified as in bodged, spark plug! The centre has been knocked out and replaced with wood!
The sump helicoil has taken out the tangs so it's pretty useless. I have a spare sump with a stripped thread so I'm going down the route of a timesert as it will be more secure than a helicoil. There are a couple of sumps on eBay but one of them the seller will not confirm the state of the threads (but still wants £85 for it) whilst the other has chipped fins. I was in touch with the seller and asked him to confirm the thread situation as they tend to strip. He checked, said they were fine and removed it from sale. The following day it was back on sale for £25 more!!!
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... I'm going down the route of a timesert as it will be more secure than a helicoil.
I'd additionally Loctite the insert preventing oils seepage...