Reply
 
Thread Tools Search this Thread
 
Old 17 July 2006, 11:02   #1
Member
 
Country: UK - England
Town: I.O.W/Bristol
Boat name: HotShot
Make: shakey
Length: 5m +
Engine: 70hp Tohatsu
Join Date: Jul 2003
Posts: 1,543
tohatsu still overheating?

Following on from my thread about my cooling tell tail...

Tell tail is now fine and has been for a while and engine seems to run ok (although it always needs revs to get her started, and sometimes struggles slightly at idle). However, when I flushed it out last night, the tell tail was quite hot, as was the block...hotter than I think it should be.

I checked the theromstat a couple of weeks ago and it was fine and I will check it again soon, but if that is not the problem, what else could be causing the engine to get too warm?

Why does it always need some revs to get her going (even if the engine is warm) and why does it sometimes (only very occasionally) konk out at idle?

Thanks in advance...
__________________

__________________
slimtim is offline   Reply With Quote
Old 17 July 2006, 12:19   #2
DM
RIBnet supporter
 
Country: UK - England
Boat name: Little Wing
Make: Searider 5.4
Length: 5m +
Engine: Tohatsu 90
Join Date: Aug 2002
Posts: 1,067
Sounds like the mixture's too lean. Try tweaking the mixture screw(s) a 1/4 of a turn.

DM
DM is offline   Reply With Quote
Old 17 July 2006, 12:29   #3
Member
 
Country: UK - England
Town: I.O.W/Bristol
Boat name: HotShot
Make: shakey
Length: 5m +
Engine: 70hp Tohatsu
Join Date: Jul 2003
Posts: 1,543
ah, interesting you mention that...I had a tweak of the screws but didn't really know what I was doing! I did suspect the mixture might be to lean but would that make it overheat?

Another question (and one I seem to have trouble finding an answer to) when I screw the screws OUT am I increasing the amount of fuel or decreasing it?

My local mechanic has told me I need to screw them right in, then out by 1.5 turns, then out 1/4 turn each until I get the best "pick up" on the throttle...trouble is I couldn't really hear any change!

Also, what should me spark plugs look like? Mine have a matt black coating, but nothing too bad...is this right or should they be cleaner? I suspect this might point to a too lean mixture?

Thanks

Tim
__________________
slimtim is offline   Reply With Quote
Old 17 July 2006, 13:05   #4
Member
 
Country: USA
Town: boston
Boat name: Miss bad 61
Make: Crapko, AKA Mako
Length: 5m +
Engine: OMC Mod50
Join Date: Apr 2006
Posts: 398
turn them in lightly till thay stop, turn out 1 1/4 turns, to 1 1/2 turns,
this will only fatten up the lowspeed circuit, but will help idle .this is not easy to do, look for a smooth idle.

to start, you need to crack the timin. when you hit the throttle Timin moves first, then the carbs come in.

brown, brown is the color you want to see. if you are lookin for a burn check
off the plugs, you can't get any thing from them if you've pulled back to the dock. you have to get the motor in the range you are checkin and pull the kill,
with out lettin off the juice. and check them on the spot.
__________________
fast fred is offline   Reply With Quote
Old 17 July 2006, 14:22   #5
Member
 
Hightower's Avatar
 
Country: UK - England
Town: Fareham
Length: 6m +
Join Date: Sep 2003
Posts: 7,855
Dark, sooty spark plugs seem to indicate a rich mixure already Tim. I would check out the cooling again and then get a tune up.

Incidently has your engine got an alarm for an overheating cooling system, if so is it sounding?
__________________
Andy

Looks Slow but is Fast
Member of the ebay Blue RIB cover club.
Hightower is offline   Reply With Quote
Old 17 July 2006, 14:33   #6
Member
 
Country: UK - Wales
Town: swansea
Boat name: Too Blue
Make: BLANK
Length: 8m +
Engine: Suzuki DT225
Join Date: Mar 2004
Posts: 12,791
Don't worry about needing some throttle to start the engine - most do!!! I would also agree black plugs mean too rich or not a hot enough spark.
__________________
codprawn is offline   Reply With Quote
Old 17 July 2006, 16:50   #7
ADS
Member
 
Country: UK - England
Town: Dorset
Length: 4m +
Join Date: Oct 2003
Posts: 1,410
Quote:
Originally Posted by codprawn
Don't worry about needing some throttle to start the engine - most do!!! I would also agree black plugs mean too rich or not a hot enough spark.
Cold start just choke for my 70HP Tohatsu, you can blip the throttle but it doesn't really need it.
__________________
ADS is offline   Reply With Quote
Old 17 July 2006, 18:09   #8
Member
 
Country: UK - England
Town: I.O.W/Bristol
Boat name: HotShot
Make: shakey
Length: 5m +
Engine: 70hp Tohatsu
Join Date: Jul 2003
Posts: 1,543
ok thanks guys. Andy, I think there is an alarm, but nothing sounds.

Can anyone tell me which way I need to screw the screws to decrease the amount of fuel in the mixture? I'm guessing by fast fred's post (thanks) that I screw out to increase fuel, so I may have them too far out at the moment. Fast fred, what do you mean by the timing and how do I go about making sure its ok?

Cheers

Tim
__________________
slimtim is offline   Reply With Quote
Old 18 July 2006, 06:37   #9
Member
 
Country: USA
Town: boston
Boat name: Miss bad 61
Make: Crapko, AKA Mako
Length: 5m +
Engine: OMC Mod50
Join Date: Apr 2006
Posts: 398
in for less out for more.when the throttel cable moves, think that one pulls,
on some Carbs crack open, next thing that needs to happen , full timeing needs to kick in, by full i mean what ever factory says for that motor, 20-22deg max, usally done with a low spot on the trottle cam.
if you havent messed with it it's prob ok.
__________________
fast fred is offline   Reply With Quote
Old 18 July 2006, 06:58   #10
Member
 
Country: UK - England
Town: nr Lymington
Boat name: JU-JU
Make: Halmatic PAC22
Length: 6m +
Engine: 140.5 Mermaid
Join Date: Sep 2003
Posts: 1,400
Tim if you arenít sure where the carb screws are it is probably best to start again, screw them fully in and do as your local mechanic suggests. With a bit of playing you will begin to get a feel for what is right andyou are unlikely to do any damage.

With regard over heating, engines do get hot but it is quite difficult to gauge how hot, I would suggest getting a multi meter with a temp probe so you can get a better feel for how hot your engine is. I have one you could borrow if you fancy a trip up the Beaulieu Des
__________________

__________________
Scary Des is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 01:54.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.