yamaha 75 2 stroke becoming a 90?

118118 · 09 March 2007, 22:26

hi,
iv got a 2005 yam 75 2 stroke on my searider, and its great. but.... anyone got any idea how its restricted to 75? anybody made it into a 90?

it seems a relatively simpleish engine.... still on carbs... and its the same block.... so it must be do-able.

is it just a simple spacer between the carbs and block thats got restrictive holes, or more serious stuff?

thanks.....

Jizm · 10 March 2007, 00:06

I may be wrong but I think it's done with carbs.

Have a look at a microfiche parts cd (ebay) and see what's different. The carbs were the difference on my 50 to take it to 60.

jyasaki · 10 March 2007, 08:37

2-stroke? I'd guess you're right on carbs with port sizes and timing running a close second.

jky

fast fred · 10 March 2007, 11:23

carbs

fast fred · 10 March 2007, 12:54

hears them 90 premix carbs, thay make a set of oil injecter ones, they are square in style.

Pete7 · 10 March 2007, 13:49

Are you sure its the same block and not a tuned 60/70 block which were smaller?

Pete

118118 · 10 March 2007, 14:27

http://www.outboards-direct.co.uk/aw...p?vid=57&rip=1

yes, its definately the same block.
if its different carbs il leave it alone,

thanks

Pete7 · 10 March 2007, 14:36

Yep worth a check though. However if the 75 is in good nick and running well would you want to mess about with it. Spring is just around the corner, seems a shame to risk lots of problems just as its warming up.

Pete

118118 · 10 March 2007, 14:39

nope, it runns very nicely, only asking unless it was something simple,
swaping carbs is someting i dont want to do.....

thanks for your replys...

John Kennett · 11 March 2007, 08:17

No use for 118118, but what's involved in upgrading an 85 to a 90?

John

Pete7 · 11 March 2007, 09:20

John, I wonder if there is any difference or if its just a marketing strategy to make buyer think they are getting more hp. Most of the 85s I have seen are pre-mix like our club boat whilst the 90s seem to be oil injection so perhaps its there to differentiate the different models.

Pete

fast fred · 14 March 2007, 10:15

for the 5hp bump, most of the time, it's a timin change, some times a main jet also.

Mugshot · 19 March 2007, 17:14

Along exactly the same lines, is it possible to do this with an E-Tec, 40hp to 60hp? If so how? Not looking to do it as a DIY job (well I'm not looking to do it at all, a mate is!) but would be done if feasible by the dealer.

mdt · 19 March 2007, 18:06

Quote:

Originally Posted by Mugshot

Along exactly the same lines, is it possible to do this with an E-Tec, 40hp to 60hp? If so how? Not looking to do it as a DIY job (well I'm not looking to do it at all, a mate is!) but would be done if feasible by the dealer.

yep as the e-tec 40 is "just" a de-tuned 60. but it is a dealer only option... god only knows what happens to any warranty etc.

chris t · 19 March 2007, 18:34

if u do get the carbs changed does it do any damage to the engine

mdt · 19 March 2007, 18:52

Quote:

Originally Posted by chris t

if u do get the carbs changed does it do any damage to the engine

there is no carbs on an e-tec ?

Mugshot · 19 March 2007, 18:55

Quote:

Originally Posted by mdt

yep as the e-tec 40 is "just" a de-tuned 60. but it is a dealer only option... god only knows what happens to any warranty etc.

Thanks for that mdt. I don't think he'll be too worried about the warranty, not sure there's that much left anyway. Think he'll be more interested in the price, but he will be delighted with the positive answer, so thanks again

chris t · 19 March 2007, 18:57

soz i just ment on any out board cos we were told that the carbs culd be changed to give some extra horses and we were wondering if this wuld damage the outboard

118118 · 19 March 2007, 20:54

not sure, but i dont think its possible for even a dealer to do the upgrade from a 40 - 60, i think its all programed directly into the computer, and cant be reprogramed. i think a new comp costs almost £2000........

i may be completly wrong, but im 90% sure..... have experienced a 50 etec, which had lots of new parts under warantee....

fast fred · 20 March 2007, 13:10

you can use any carb or carbs, as long as you can make them fit, and they are jetted right.
this is a 70hp case with 90hp carbs, makes 98 to 105hp pulls to 8000rpms
dapendin on the tune-up

and just in case thats not enuff , hears a 6pack setup

what you can do is limited to just that, What you can do.