Ryan Vogels
Jet Boat Addict
- Messages
- 39
- Reaction score
- 23
- Points
- 87
- Location
- Appleton, WI
- Boat Make
- Yamaha
- Year
- 2016
- Boat Model
- AR
- Boat Length
- 24
I had posted a lot of info on the topic on the unmentionable "other" site. I am open to any questions that people may have on the topic. I prefer that this topic does not get a lot of doubters. There is ZERO reason to double this. My combination engine is up and running. I do not have much time on it yet, as the weather in Wisconsin has not allowed. I will do my best to attempt to keep this post updated. I also have a lot of pictures from the process.
My research started after I bought my SX230 HO with a bad engine. The previous owner, who may be on this site, had catastrophic engine failure. The engine threw a rod at wide open throttle. The issue was with the number 4 cylinder (closest to the back of the boat). Previous owner had said he was quoted $10k by a dealer to fix the issue. The head was off of the crank case when I purchased it, but the case was still in take. When I took it apart, the damage was pretty severe. A chunk of the piston had broken off, part of the wrist pin had broken off, and the rod split in two pieces. This in turn, turn in to little pieces because the engine was spinning so fast. There was a chunk of metal taken out of the "windage tray." A chunk of the block was missing that allowed oil to flow from the oil liter. The cylinder had a "dip" in it.
With those findings I started looking into all possible options including getting the blocked welded, ordering a SBT engine, or looking for a donor engine. I sent picture of the block to SBT. They said they would take the block in as in condition with about a $350 welding charge. I also looking locally into have the block repaired. The blocks are nicasil plated. This means that cant really be bored out, and then slap some new pistons in. The have to be replated instead of bored out. The replating the cylinders cannot be done on individual cylinders, it is an all or nothing job. So, both options could have been fairly pricey.
I then stumbled across an engine from a VX110 Yamaha Jetski. It was pulled from a ski that had about 600 hours on it. It came with the case, pistons, rods, crankshaft, etc. There was no head with it. The VX110 jetski's only have 110HP. I knew that would not work having one underpowered engine. So I wanted to figure out why, because they claimed the same engine size (1052cc) Just to be clear, the 140 HP engine is under 1000 cc. The displacement is in fact different.
So I started my research on the differences. The bore and the stroke of the engine are exactly the same. This meant that the crank, pistons, and rods were all the same size. But, the compression ratio was lower. The 160HP engine runs an 11.9 compression ration. The Jetski engine is 11.4 if I remember correctly. This was a bit concerning because I couldn't figure out why there was a difference. The bottom end of the engine utilizes the same sized parts, had the same displacement, and had the same bore and stroke. To this day I do not know exactly why there is a difference. It may be in the head or head gasket.
From there I wanted to figure out where the extra power came from. Obviously some would come with the higher compression. But, that is now where near the extra 50 hp. I discovered that the valves are the same between the heads. So it is no issue with airflow threw the head. The head and valves are the same between the two. I then found out that the cams are different. I don't have any exact specs, but I assume the cams have bigger lobes and thus open the valves further.
I also knew that the Jetski engine only revved to about 7k RPMs and the HO motors went to about 10k RPM. This would obviously equate to more power. So I knew that timing and the computer that controlled the engines were different.
So, I kept exploring. I found the intakes to be VERY VERY DIFFERENT. The HO motors utilize 4 throttle bodies that are synced together and are place right over the intake ports on the head. The Jetski motor has one throttle body that feeds a large intake plenum that in turn feeds the 4 cylinders.
I obviously had all of the HO parts. So using the parts that were different would be easy. I only had a few bent valves to deal with on the head. So I was about ready to pull the trigger on the used block. I started pricing out the parts I knew I would need. I discovered that the crank shaft is the EXACT same part number. So I new I had a good crank shaft. Used ones go for around $500. So I pulled the trigger on the VX110 engine. I got it for $500, and the shipping another $100. To my delight the engine was in good shape when I received it.
I tore the engine apart to find the cylinders in great shape. The crankshaft was also in great shape. I inspected the blocks to look for differences. The only one I found was a water inlet pipe for the block. The HO motor comes straight out. The Jetski engine had a bend in it. I had noticed this in prior research. This was an easy fix. I heated the pipe up and pulled the pipes out. I then put the appropriate pipe in its place. All sensors where the same places.
I still had to deal with the pistons and rods. Could I use the Jetski ones in place of the HO motors broken parts? I carefully measured them to check for size difference. The size was the same. I used a very high quality scale to weigh them. There was a fairly large difference in weight. I figured the excess weight could be problematic at sock a high RPM. So I opted to use HO rods and pistons.
The cylinders seemed to be in good shape, but I wanted to make sure. So I had the Jetski blocked slightly honed. (father is a machinist) to ensure they were ask close to new without replating as possible. I also had the crankshaft polished. This was personal preference, but probably not necessary.
This created bearing concerns. The bearing are sold as a colorcode. Not sold by the size. I don't want to ramble to much, but some careful calculating led me to a bearing that was slightly larger.
From here I started re assembly. The process was pretty smooth. The biggest issue was figuring out timing. The dealer did not mark the chain or gears to ensure proper reinstallation. I can give more details on this if needed. There was was one oil cooler mount that was different between the two engines. One used bigger bolts than the other. So I drilled out and tapped the holes of the jetski block to accept the larger bolts. I checked compression at this point. I had over 180psi in each cylinder.
Dropping the engine in the boat was fairly smooth. After reassembling everything I crossed my fingers a turned the key. (to much lag to continue. will edit it in later or add another post)
Edit to add part 2-
The engine would not start. It would turn over and give a small fire every few seconds. So I started to troubleshoot. My fear was that timing was off. It just sounded that way. So I worked the engine into TDC on cylinder one. I reviewed the cam timing marks which were pretty much dead on. I checked all of the plugs to make sure they had spark. I pulled off the into and turned it over to see that all four injectors were firing. All of that was fine. So I still seemed to be timing. BUT, the timing marks seems to be dead on.
Then I started swapping parts from one engine to another. I changed some of the sensors, and finally I swapped the intake as a whole. Still no luck. So I stripped down each engine to the point of taking off the valve cover. I then put each engine at TDC on cylinder one. My timing chain was indeed on correct. I was pretty sure it had to be with the compression readings of over 180PSI on each.
I started to wonder if it could be the computer that was faulty. After all, I had no idea what caused the engine to blow up for the previous owner. I slept on it a few days, and it finally dawned on me. there is one other thing that controls timing in these engines.... The pickup coils and the flywheel.
With the engine still in the boat, I removed the exhaust and the stator cover. I then looked over the pick up coils and fly wheel. I HATE ADMITTING THIS, but I noticed some differences in the flywheels. I used the flywheel that was on the crankshaft from the Jetski. I only did a quick lookover of each flywheel before deciding on using the jetski crankshaft/etc. My quick initial inspection was not good enough! So, with the engine still in the boat I removed the flywheel and pressed on the boat flywheel. After re assembly time, it was time again to turn the key.
After a few seconds of turning over, my Franken-engine roared to life! Needless to say I was a happy happy man, though still disappointed in my self for missing this flywheel issue WAY back in the beginning.
Now comes time to break in the engine, and get to know it a little better! There is yet another part coming to this story. You may want to get tissues ready for part 3....
My research started after I bought my SX230 HO with a bad engine. The previous owner, who may be on this site, had catastrophic engine failure. The engine threw a rod at wide open throttle. The issue was with the number 4 cylinder (closest to the back of the boat). Previous owner had said he was quoted $10k by a dealer to fix the issue. The head was off of the crank case when I purchased it, but the case was still in take. When I took it apart, the damage was pretty severe. A chunk of the piston had broken off, part of the wrist pin had broken off, and the rod split in two pieces. This in turn, turn in to little pieces because the engine was spinning so fast. There was a chunk of metal taken out of the "windage tray." A chunk of the block was missing that allowed oil to flow from the oil liter. The cylinder had a "dip" in it.
With those findings I started looking into all possible options including getting the blocked welded, ordering a SBT engine, or looking for a donor engine. I sent picture of the block to SBT. They said they would take the block in as in condition with about a $350 welding charge. I also looking locally into have the block repaired. The blocks are nicasil plated. This means that cant really be bored out, and then slap some new pistons in. The have to be replated instead of bored out. The replating the cylinders cannot be done on individual cylinders, it is an all or nothing job. So, both options could have been fairly pricey.
I then stumbled across an engine from a VX110 Yamaha Jetski. It was pulled from a ski that had about 600 hours on it. It came with the case, pistons, rods, crankshaft, etc. There was no head with it. The VX110 jetski's only have 110HP. I knew that would not work having one underpowered engine. So I wanted to figure out why, because they claimed the same engine size (1052cc) Just to be clear, the 140 HP engine is under 1000 cc. The displacement is in fact different.
So I started my research on the differences. The bore and the stroke of the engine are exactly the same. This meant that the crank, pistons, and rods were all the same size. But, the compression ratio was lower. The 160HP engine runs an 11.9 compression ration. The Jetski engine is 11.4 if I remember correctly. This was a bit concerning because I couldn't figure out why there was a difference. The bottom end of the engine utilizes the same sized parts, had the same displacement, and had the same bore and stroke. To this day I do not know exactly why there is a difference. It may be in the head or head gasket.
From there I wanted to figure out where the extra power came from. Obviously some would come with the higher compression. But, that is now where near the extra 50 hp. I discovered that the valves are the same between the heads. So it is no issue with airflow threw the head. The head and valves are the same between the two. I then found out that the cams are different. I don't have any exact specs, but I assume the cams have bigger lobes and thus open the valves further.
I also knew that the Jetski engine only revved to about 7k RPMs and the HO motors went to about 10k RPM. This would obviously equate to more power. So I knew that timing and the computer that controlled the engines were different.
So, I kept exploring. I found the intakes to be VERY VERY DIFFERENT. The HO motors utilize 4 throttle bodies that are synced together and are place right over the intake ports on the head. The Jetski motor has one throttle body that feeds a large intake plenum that in turn feeds the 4 cylinders.
I obviously had all of the HO parts. So using the parts that were different would be easy. I only had a few bent valves to deal with on the head. So I was about ready to pull the trigger on the used block. I started pricing out the parts I knew I would need. I discovered that the crank shaft is the EXACT same part number. So I new I had a good crank shaft. Used ones go for around $500. So I pulled the trigger on the VX110 engine. I got it for $500, and the shipping another $100. To my delight the engine was in good shape when I received it.
I tore the engine apart to find the cylinders in great shape. The crankshaft was also in great shape. I inspected the blocks to look for differences. The only one I found was a water inlet pipe for the block. The HO motor comes straight out. The Jetski engine had a bend in it. I had noticed this in prior research. This was an easy fix. I heated the pipe up and pulled the pipes out. I then put the appropriate pipe in its place. All sensors where the same places.
I still had to deal with the pistons and rods. Could I use the Jetski ones in place of the HO motors broken parts? I carefully measured them to check for size difference. The size was the same. I used a very high quality scale to weigh them. There was a fairly large difference in weight. I figured the excess weight could be problematic at sock a high RPM. So I opted to use HO rods and pistons.
The cylinders seemed to be in good shape, but I wanted to make sure. So I had the Jetski blocked slightly honed. (father is a machinist) to ensure they were ask close to new without replating as possible. I also had the crankshaft polished. This was personal preference, but probably not necessary.
This created bearing concerns. The bearing are sold as a colorcode. Not sold by the size. I don't want to ramble to much, but some careful calculating led me to a bearing that was slightly larger.
From here I started re assembly. The process was pretty smooth. The biggest issue was figuring out timing. The dealer did not mark the chain or gears to ensure proper reinstallation. I can give more details on this if needed. There was was one oil cooler mount that was different between the two engines. One used bigger bolts than the other. So I drilled out and tapped the holes of the jetski block to accept the larger bolts. I checked compression at this point. I had over 180psi in each cylinder.
Dropping the engine in the boat was fairly smooth. After reassembling everything I crossed my fingers a turned the key. (to much lag to continue. will edit it in later or add another post)
Edit to add part 2-
The engine would not start. It would turn over and give a small fire every few seconds. So I started to troubleshoot. My fear was that timing was off. It just sounded that way. So I worked the engine into TDC on cylinder one. I reviewed the cam timing marks which were pretty much dead on. I checked all of the plugs to make sure they had spark. I pulled off the into and turned it over to see that all four injectors were firing. All of that was fine. So I still seemed to be timing. BUT, the timing marks seems to be dead on.
Then I started swapping parts from one engine to another. I changed some of the sensors, and finally I swapped the intake as a whole. Still no luck. So I stripped down each engine to the point of taking off the valve cover. I then put each engine at TDC on cylinder one. My timing chain was indeed on correct. I was pretty sure it had to be with the compression readings of over 180PSI on each.
I started to wonder if it could be the computer that was faulty. After all, I had no idea what caused the engine to blow up for the previous owner. I slept on it a few days, and it finally dawned on me. there is one other thing that controls timing in these engines.... The pickup coils and the flywheel.
With the engine still in the boat, I removed the exhaust and the stator cover. I then looked over the pick up coils and fly wheel. I HATE ADMITTING THIS, but I noticed some differences in the flywheels. I used the flywheel that was on the crankshaft from the Jetski. I only did a quick lookover of each flywheel before deciding on using the jetski crankshaft/etc. My quick initial inspection was not good enough! So, with the engine still in the boat I removed the flywheel and pressed on the boat flywheel. After re assembly time, it was time again to turn the key.
After a few seconds of turning over, my Franken-engine roared to life! Needless to say I was a happy happy man, though still disappointed in my self for missing this flywheel issue WAY back in the beginning.
Now comes time to break in the engine, and get to know it a little better! There is yet another part coming to this story. You may want to get tissues ready for part 3....
Last edited:
Thanks Jeff.
