Tohatsu's M Bolts.-

[Sea Rider]

Will a 13 mm head hex metric bolt with 0.8 mm diameter body, is a M10 bolt ?

Happy Boating

 

[pvanv]

Might be. Also could be 8 mm. What bolt do you need? They are listed in the parts catalogs... The part number decodes to be the thread diameter and length.

 

[Sea Rider]

Paul,

I'm referring to the 18 HP cylinder head bolts, parts manual doesn't specify the M size just the part code. Ordered a M10 Time Sert pack of 10 and the Amazon's seller morons have shipped 0.9 mm internal diam inserts, don't know to which hex bolt nut corresponds to, but way larger in diam than a M10 bolt.

The original bolt swings inside the insert sent, both being 1.5 thread pitched matches well.



A M10 insert should match same13 mm hex nut with 0.8 mm diam bolt shown in pic. BTY which M bolt number corresponds to the bolts found on the exhaust cover. Can you check both up. This data is of extreme importance to know the correct M bolt insert size needed for both applications..

Happy Boating

 

[pvanv]

Luis,

The hex head size tells you nothing. You need to know diameter, pitch, and length... and whether the bolt is shouldered... and if so, what kind of shoulder.

Most Tohatsu bolts with 10mm head are 6mm bolts.

Typical Metric bolts follow the following chart: [h=3]Hexagon Head Cap Screws[/h]

Dimensions in millimeters

Head Height, Max “K”	2.8	3.5	4	5.5	7	8	9	10	13	15
Across Flats, “S”	.7	8	10	13	17	19	22	24	30	36
Pitch, “P”	.7	.8	1	1.25	1.5	1.75	2	2	2.5	3

Thread Size ‘D’ M4 M5 M6 M8 M10 M12 M14 M16 M20 M24

 

[pvanv]

Below is a partial list of metric sizes (diameter-pitch) Fastener Mart offers (be sure to search our store for other sizes)…

M1.4-0.3
M2-0.4
M2.5-0.45
M3-0.5
M3.5-0.6
M4-0.7
M5-0.8
M6-1.0
M7-1.0
M8-1.25	M8-1.0
M10-1.5	M10-1.25	M10-1.0
M12-1.75	M12-1.5	M12-1.25
M14-2.0	M14-1.5
M16-2.0	M16-1.5
M18-2.5	M18-1.5
M20-2.5	M20-1.5
M22-2.5
M24-3.0	M24-2.0
M30-3.5
M36-4.0

Table 5. List of common metric sizes.
Coarse Fine Extra Fine

 

[pvanv]

View attachment bolt-information2.pdf

 

[Sea Rider]

Thanks Paul,

Have written the Time Sert Company and these guys are so darn cooperative that we were playing ping pong emailing with each other with no avail at the moment. Incredible that such Company doesn't know what they sell sometimes same as the large river Company..

Question does the pic corresponds to a M8 or M10 Tohatsu bolt ?



Seems was packed and labeled wrongly with a M10 x 1.5 x 16 sticker which turned useless. Seems it's for a M11 bolt having 0.9 in diam, that's if a 0.9 mm diam threaded bolt corresponds to a M11 bolt ?

What the info sent does not specify is which is the thread diam in mm, not pitch of a M10 bolt if a M10 bolt same as pic happens to be the bolt that bolts the cylinder head to the crankcase. Knowing the correct M size espec will know what to order...

Would you say that a bolt being 1.0 thread pitched is super fine compared to a 1.5 pitch. In other words the threads are very close to each other, right ? Thought that there were only 1.5 & 1.25 thread pitches.

Happy Boating

 

[pvanv]

Go with the part number, and decode it: 9161190840M

9= Bolt
161= Threaded, with hex head
1= Dacrotized (coated)
9= Heat Treated
08= 8 mm diameter
40= 40mm total length

Standard pitch would be 1.25 mm per thread; 1mm would be fine thread.

 

[Sea Rider]

Paul,

Something doesn't add up...

The 2 strokes Service Manual mentions on page 2-5 severa M bolts sizes which ranges from M4 to M10, a 9 Bolt iis not listed. Question : will a 9 bolt correspond to a M9 size ? If not will need to know :

1-Cylinder Head Bolt # 916119-0840M / M bolt size equivalence.

2-Exhaust Cover Bolt # 910114-0625M / M bolt size equivalence.

Time Sert onllly works with precise M bolt sizes, don't even know the internal diams of their inserts and won't even measure one for you say a M10 insert, beides the guy that answers their tech emails is lost around mars...

Do you think Tohatsu USA may know, if not will need to contact Tohatsu Japan and ask them or won't be seing the light at the end of the tunnel any time soon LOL!!

Happy Boating

 

[pvanv]

0840 is an M8 or 8mm bolt. That's the head bolts.
0625 is an M6 or 6mm bolt. That's for the exhaust cover. Probably has a 10mm head.

 

[Sea Rider]

Paul,

Thanks, but still something doesn't add up...

if you look at the data on page 2-5 where M6 and M8 bolts sizes are listed, will see that the torque force of a M8 bolt is 11-15 NM, way less than stamped on the head which states 25 NM, middle torque which matches the M10 size 23-31 NM spot on.

Same applies to the exhaust cover torque force, 8NM is stamped on the cover which none of the M6 or M8 bolt handles, strange. What are your thoughts about this tbolt size/torque force tech controversy.

Wrote Tohatsu Japan Tech Department twice for both bolts M inquiry seems their server is down, received same twice back answer : Request Time Out - Server Time Out waiting for the HTTP request from the client.

Happy Boating

 

[pvanv]

Luis,

To clear up your sizing issue, you can just go to the hardware store and buy some M6, M8, and M10 bolts and compare them.

 

[LTEAK]

pvanv, can you help me decode this Tohatsu bolt number?: 910113-5820

Parsed: 9-101-1-3 58-20

From your list above it looks to be a dacronized bolt, 20 mm long, but what do the other numbers mean? Particularly, what is the diameter? It seems to be 7.5mm measured with a caliper, but I've never heard of that bolt diameter before. (Item 18-5 in the parts manual for a Tohatsu M40C.)

(Heads sheared off. I need to extract them and probably chase the threads in the holes. I'm in a remote location, so need order a tap ahead of time.)

Is there a table somewhere online for decoding Tohatsu bolt part numbers?