Zapcat slow speed?????

[Blind_Mel]

What kind of speed should I get from a 50hp Tohatsu and Zapcat? I'm getting 32knots and thats to slow. The engine is a 2007mod and i haven't done anything too it yet, what can i do and is that a normal speed for that boat engine combo? the prop is 11x15 steel prop. What should i do? and where can i get info on tuning the engine.. The revlimiter is not cut is that why i can't get more speed?

Hope for some help here...

[rib-x450]

I have a small memory tacho on mine reocrds the highest rpm which helps see if your near max rpms.

There are other posts about these on the site.

Just wrap it on an HT lead, dead easy..........

[Easyrider]

I presume that its just you and a passenger in the boat. If you carry 3/4 people it drastically reduces the speed due to the non parallel hijackers ploughing through the water. For 2 people aboard, the biggest bearing on the speed in these boats is the trim angle/weight distribution. On your rig you need it to be on the 2nd hole out from the transom on the trim(or 3rd if you carry more weight up front) and your passenger needs to sit towards the rear for high speeds/flat water . Try that and let us know.
Its worth getting a tiny tach rev counter so you can check your revs whilst on the move.
I can gain 400 revs when my passenger moves about 3ft back which makes a hell of a difference.

[samt]

New prop. I had the same prop on my 4m avon searider rib with a mariner 40 and was getting 32knots.

The RR zapcats use a stainless semi cleaver prop.

http://www.zapcat-racing.com/la/2881

I'm sure they would be happy to help.

[Blind_Mel]

I tried with only one person in the boat and two... I can't get the rpm up.. The engine is almost new.. I was wondering wat speed I can get aout of the box with this boat... I't sounds like i can't get high rpm.. I tested the compression and it's 120... I was hoping to get 45knots but do you have to tune the engine to get this speed... Mabye is the ignition or the carburators thats need some adjustment.... The prop i bougt from winracer in Norway and it should be the right prop.. I'm gonne mesure the rpm and get back but i'm almost sure that the rpm is to low... And how know if the carburator or ignition is wrong? i'l try to cut the revlimiter tomorow and see what hapens....

[Blind_Mel]

yes I know but with this prop I should get more speed than 32knots I know other peopel with the same prop that says i should get 45knots or more.. I cant get the high rpm... the engine is almost new.. Maby i have to adjust the ignition or the carburators... How du I do that? and how do I know if it's wrong?

[Nos4r2]

Originally Posted by Blind_Mel

yes I know but with this prop I should get more speed than 32knots I know other peopel with the same prop that says i should get 45knots or more.. I cant get the high rpm... the engine is almost new.. Maby i have to adjust the ignition or the carburators... How du I do that? and how do I know if it's wrong?

If you don't know how to, don't. Pay an engineer or you'll face an even bigger bill to repair it.

[ian parkes]

Originally Posted by Blind_Mel

yes I know but with this prop I should get more speed than 32knots I know other peopel with the same prop that says i should get 45knots or more.. I cant get the high rpm... the engine is almost new.. Maby i have to adjust the ignition or the carburators... How du I do that? and how do I know if it's wrong?

Do as Nos says , and if if the engine is new you should be takin it a bit easy on it

They say run new engine in on 25-1 , having just done that with a new tohatsu I would say its not necessary on a light boat .

have you checked and cleaned the plugs ?

If your engine has oiled a plug and is running on 2 cyls , believe it or not you may not notice untill you try and give it full throttle and then it just feels down on power as if its a 30 , it doesn't run rough at all . That caut me out first time , and having recently run my toghatsu in by the book it does oil a plug almost every time you go out for a while ,always one of the two lower cyls .

Forget the rev limiter that only stops it over revving , and you are not reaching that by the sounds of it .

[Easyrider]

If your revs are down with a light load then i'd agree with Ian- I would change the plugs for new ones. Checking the ignition is easy

Heres a pdf file on it.

But it youre unsure in any way then dont do it. Theres no harm in asking for advice though

[benc]

Gray and I have a Zapcat, with an unmodified engine - and we clocked it at 43.1 knots last year when we were testing it out with two of us in it (and im not a small guy ). Definately sounds like you're not hitting revs, check the plugs, and the engine height.