alexandra
21.06.2021 19:50:09
There must be some elegant way of desiging a four stroke so that it can be stored or even run at any angle.
See full version: The laying down of four strokes
There must be some elegant way of desiging a four stroke so that it can be stored or even run at any angle.
Engine designers will design the engine so that it can tolerate a certain degree of inclination and position without causing the oil to escape the sump; this is why there a limitation in the way it can be positioned side down.
Unfortunately, the oil has to stay in the sump on the bottom of the engine on all 4 stroke engine whether big or small; this is one of the two basic differences between 2 and 4 stroke engines. here
Just a minute.
Have you (any of you, not aimed at any one in particular) noticed that most outboards (including 4 strokes) have two tilt settings so that you can leave the motor slightly tilted or at about 50°?
They are absolutely fine like that. My last motor and current motor don't object.
Even if you have steering swivel on, the tilt doesn't cause catastrophic and lasting damage.
If you know about engines you'll know that 2 strokes do not have a sump with a volume of oil at the bottom.
4 strokes do.
They also have valve gear and a camshaft to operate the valve gear. Normally the side that has the valve gear will have an open chamber through which the oil could run if laid on that side. One valve will normally be open at most points of the cycle so oil will have free access to the cylinder via that route. It only has to run down the oil stem. If you are really determined you could let the oil run back up the bores past the pistion rings. But that would take some definite effort.
As Niander says, each engine has it's own foibles and requirements which are laid out in the handbook and the usually on the motor itself.
If you can't be arsed to learn those requirements. More fool you. more
Four strokes can be dry-sumped, but that is a very expensive and weighty answer to the problem of not learning which side to lay it down.
LIT-18616-01-81 Service Repair Manual Application: 1998-1999 98-99 40HP (40-HP) & 50HP (50-HP) 40W 50W Yamaha Marine Outboard 2-Stroke Item Model Names: 40-W, 50-W, 40VMH, 40VMHD, 40VMHO, 40VMO, 40VWH, 40VE, 40VEO, 40VEHTO, 40VET, C40MH, 40MH, C40ER, 40ER, P40TH, C40TR, 40VETO, 50HMHO, 50HMHD, 50HMO, 50HMDO, 50HWHD, 50HEDO, 50HET, 50HETO, 40TR, 50ER, C50TR, 50TR Covers USA, Canada and wold wide models.
LIT-18616-02-54 Service Repair Manual Application: 2004-2005 Yamaha Marine Outboard 2.5HP (2.5-HP) F2.5C (F2.5-C, F 2.5C) F2.5MH 4-Stroke Engines.
LIT-18616-02-66 Service Repair Manual Application: 2004 04' & 2005 Yamaha Marine Outboard 70HP (70-HP) 2-Stroke Engines. Model name 70BETO, USA and Canada name 70TR 70C (70-C).
Since there is no concensus here, I will do what my manual recommends (not using the lever when trailering) and what I have done with my other motors (use the transom saver). Thanks for the input. ( I will get the one with the rubber shock absorber to compromise) [links]
Re: Trailering a Yamaha 115 HP question power tilt up or not.
When the motor is tilted all the way up, it is more or less balanced, meaning the majority of the mass is focused down on the transom. Not violently wrenching it fore & aft as transom saver mfgs would have you believe.
"The most prevalent argument against them centers on the fact that a transom saver transfers the weight and energy from an area that is designed to handle it (the transom) to an area that is not (the trailer). Additionally, while the boat and motor move together, the boat and trailer move independently from each other, causing road vibrations to be transferred back to the outdrive where they can potentially cause even more damage."
And there you have your answer in one post. All you need is a quarter to flip and you will know which way to go.
I use a detachable trailering bracket made specifically for my motor. It's inserted into the trim holes in the transom bracket, and the motor is lowered onto it. If I didn't have this gizmo I would use a transom saver, a.k.a. motor defloperizer.
Removed and checked carbs. They were pristine inside and out and no issues. Removed fuel pumps and checked. Diaphragms were intact and no apparent issues with fuel pumps.
It just seems that the fuel delivery system is not keeping up with the demand. Maybe electrical?? [links]
I recently acquired a new to me boat and am trying to trace down some engine problems I am having with it. Model #F100 TLRX. Test drove the boat and it ran good before I completed the purchase. Drove it home (About 300 miles) and took it out on the water a few days later. Ran ok at low speed but would bog down badly and cut out at about half throttle and above. The longer I ran it the worse it got. Barely limped back to the boat dock when I finally took it in.
What I know about the motor: The previous owner had recently rebuilt the motor and it had less than 2 hours run time on the rebuild. The motor started running poorly so he took it into the marine mechanic who put new plugs in it and completely rebuilt and synced the carbs. Boat ran good shortly but he had to take it back in again because it was doing exactly what it is now according to the info written on the receipt he gave me of work done by the shop.
They told him that somehow the carbs had gotten out of sync after they were synced previously. They resynced the carbs, did not charge him, and sent him on his way. This is where I come into the picture. Test drove the boat, bought the boat, now it is doing exactly what it was for the previous owner prior to him taking it to the marine mechanic to have carbs rebuilt and synced.
I messaged him to get some more info and he told me it ran great after they resynced the carbs (which I can attest to). IT didn't make sense to me but I thought perhaps the carbs got out of sync and if I resync them then it should run fine, right? I purchased a Carbtune II carburetor sync tool and proceeded to sync the carbs. Engine still bogging down at full throttle.
Checked the tank and found that it was missing an O-ring on the fuel cap and had allowed water into the fuel. I replaced the fuel separator, drained the tank, and replaced the fuel. I thought this had to be the cause of the bad running motor. Deduced that the road trip home had mixed the water up into the fuel from the bottom of the tank and that is why it ran well on the test run and poorly when I got home. I was 100% wrong. The boat still ran poorly.
I removed the suction tube from the onboard tank and it was clean and unobstructed. I did note that there was a check valve on the fitting where the suction tube attached to the tank. IT seemed to work properly and I was able to depress the ball in the valve and it would return to position without issue when I released it. I assume the vent to the tank is unobstructed because I removed the fuel cap when the motor was running and it had no effect on the poor running motor. I thought it could perhaps be sucking air somewhere in the fuel line but all Fuel line clamps were tight.